Maternal Folic Acid and Dietary Folate Intake in Relation to Sex Ratio at Birth and Sex-Specific Birth Weight in China.

BACKGROUND: It is well-established that prenatal folic acid supplements can reduce neural tube defects. However, the associations between folic acid supplementation, dietary folate intake, and overall folate intake with sex-specific birth outcomes are not yet fully understood. OBJECTIVES: This study aims to investigate the association of periconceptional folic acid supplement, dietary folate, and total folate intake with the sex ratio at birth and sex-specific birth weight. METHODS: Data were sourced from a cross-sectional survey conducted between August and December 2013 in Northwest China, involving 7318 infants and their mothers, recruited using a stratified multistage random sampling method. Folic acid supplements (400 µg/d) were ascertained via a retrospective in-person interview. Dietary folate was evaluated using a validated food frequency questionnaire. Birth outcomes, including sex and weight at birth, were obtained from the Medical Certificate of Birth. Generalized linear models were employed to calculate relative risks (RRs) or differences with 95% confidence intervals (CIs). RESULTS: No association or dose-response relationship was observed between folic acid supplement, dietary folate, and total folate intake during periconception and the likelihood of male births. However, women who took folic acid supplements during pre- and post-conception were associated with an increased male birth weight by 52.8 (8.1 to 97.5) g. Additionally, the total folate intake during periconception was associated with birth weight for males (upper vs. lower tertile: ß = 38.8, 95%CI: 5.0 to 72.5 g, p-trend = 0.024) and females (upper vs. lower tertile: ß = 42.4, 95%CI: 6.7 to 78.1; p-trend = 0.022). CONCLUSIONS: Our findings indicate that periconceptional total folate intake does not correlate with sex ratio at birth but was positively linked to infant birth weights, regardless of gender. These findings offer novel insights into potential benefits of total folate intake, beyond the prevention of neural tube defects, for policymakers and public health.

The Impact of the COVID-19 Pandemic on the Sex Ratio at Birth in Ireland.

OBJECTIVES: The sex ratio at birth (SRB), calculated as male divided by total live births, is an important indicator of population health. Typically, male live births slightly outnumber female live births. Population events, including pandemics, can alter the SRB, with effects sometimes evident 9 months post-event, potentially due to changes in sexual behavior and/or stress levels. This study investigates the impact of the COVID-19 pandemic on the SRB in the Republic of Ireland. METHODS: Publicly available monthly live birth data for Ireland were obtained from the Central Statistics Office for the period 2015 to 2021. Time series analysis predicted the SRB for 2020 using data from 2015 to 2019, with comparisons made between observed and predicted values. RESULTS: In December 2020, 9 months after the March 2020 COVID-19 declaration, the observed SRB sharply fell to 49.44% (97.80 males for every 100 females), below the 95% prediction interval of 50.31% to 52.15%, significantly deviating from the expected male predominance. December 2020 also recorded the lowest average daily number of births (n = 145) in the study period. CONCLUSION: The sharp decline in the SRB in December 2020, alongside the lowest birth count, suggests reduced sexual intercourse at the population level, particularly in March 2020, aligning with recommendations from Ireland's Health Service Executive (HSE). The HSE advocated precautionary measures such as limiting partnered sex in March 2020 to mitigate the spread of COVID-19. These findings highlight the pandemic's potential impact on population dynamics and stress the importance of SRB monitoring as a low-cost and readily available health indicator, especially during national crises.

Induced abortion after advent of fetal sex detection technology and child sex at birth.

BACKGROUND: National level Sex Ratio at Birth (SRB) is normal in Bangladesh despite its patriarchal social structures, strong son preference, and low fertility level, widely recognized as preconditions for Gender-Biased Sex Selection (GBSS). To better understand this anomaly, we examine the trend in SRB in a sub-district in Bangladesh and assess the impact of the introduction of fetal sex-detection technology and the history of induced abortion on child sex using longitudinal data. METHODS: We have used secondary data collected routinely by icddr, b's Matlab Health and Demographic Surveillance System (HDSS) between 1982 and 2018. All births occurring during this period (N = 206,390) were included in the analyses. We calculated the SRB and used multivariate logistic regression analyses to assess the likelihood of birth of a male child before and after the introduction of ultrasonogram in Matlab. RESULTS: Overall, SRB was within the natural limit (106) during 1982-2018 in Matlab. SRB among women with a history of induced abortion was 109.3 before the introduction of ultrasonography in 2001 and 113.5 - after 2001. Women's history of induced abortion prior to introduction of ultrasonogram (1982-2000) increased the likelihood of birth of a male child 1.06 times (AOR 1.06; 95% CI- 1.01-1.11). In the period after, however, this likelihood was 1.08 (AOR 1.08; 95% CI- 1.02-1.15). CONCLUSIONS: In a context with normal SRB, it was found to be skewed among women who had induced abortion. SRB was relatively more skewed among such women after the advent of ultrasonogram compared to a period without ultrasonogram. Moreover, induced abortion after introduction of fetal sex determination technology increased the likelihood of birth of a male child. These findings suggest the plausibility of GBSS in a sub-group. Further research is needed, particularly in regions with skewed SRB to examine whether GBSS is indeed a threat to Bangladesh.

Sex ratio at birth across 100 years in Sweden and risk of cardiovascular disease and all-cause mortality - a national register study.

The human sex ratio at birth (SRB) undergoes temporary changes around a mean proportion of 0.51 male births. SRB has been well studied for historical, geographical, and secular trends, but until now not linked to health outcomes in the total population, e.g. for cardiovascular disease (CVD) or mortality during follow-up of birth cohorts. We used linkage analysis based on national registers in Sweden that cover all births from 1900 to 2016. SRB at birth was calculated by every 10-year birth cohort in all survivors living in 1997 for a follow-up analysis of risk of CVD and mortality with data from national registers. When the highest quartile of SRB was used as reference, a slightly increased risk of fatal CVD (HR 1.03 (95% confidence intervals, CI): 1.02-1.04), non-fatal CVD (HR 1.01; 95%CI: 1.01-1.02) and mortality (HR 1.02; 95%CI, 1.01-1.03) was found after full adjustments in men belonging to the lowest SRB quartile. A similar pattern was also found for fatal CHD in women. in the lowest SBR quartile compared to the highest, HR 1.03 (95%CI: 1.02-1.05). In conclusion, in birth cohorts with a relatively lower than expected number of males born, long-term adverse health effects were observed with slightly increased cardiovascular risk and total mortality at the population level. This could indicate that men belonging to so-called "culled cohorts" in a developed country during the 20th century are characterized by a slightly increased risk that could reflect negative early life influences and environmental exposures in pregnant women resulting in selective loss of male embryos or fetuses. In a public health perspective SRB could be of some importance to monitor as an aspect of birth statistics linked to relatively minor population health effects.

Sex Ratio at Birth after Concurrent Events of Earthquakes and the COVID-19 Pandemic in Croatia.

The sex ratio at birth (ratio of males to females) has been known to be affected by exogenous shocks such as wars, pollution, natural catastrophes, economic crises, and others. Among these stressful events, both earthquakes and the COVID-19 pandemic have been reported to lower the sex ratio at birth. In this article, a rather unusual situation of two episodes of simultaneous events of COVID-19 lockdown and earthquakes approximately nine months apart (March and December of 2020) is investigated to assess whether they were associated with a bias in sex ratio at birth 3-5 months later (in utero loss) and 9 months later (loss at conception) in Croatia. The monthly time series of sex ratio at birth, total number of births, and total number of both male and female births from January 2010 to December 2021 were analyzed. Seasonally adjusted autoregressive moving-average models were used to estimate the functional form of the time series from January 2010 to February 2020. These results were used to predict the future values of the series until December 2021 and to compare them with the actual values. For all series used, there was no indication of deviation from the values predicted by the models, neither for 3-5 months nor for 9 months after the COVID-19 lockdown and earthquake events. The possible mechanisms of the absence of bias, such as the threshold of the stressful events and its localized reach, as well as the statistical methods employed, are discussed.

Seasonal variation in air pollutant levels and its effects on the sex ratio at birth on Fukue island, Japan.

BACKGROUND: In general, a slightly higher number of boys are born than girls, and the sex ratio at birth (number of male births/number of female births) is reported to be 1.03-1.07 in many countries. However, pregnant women exposed to high levels of atmospheric particulate matter have a reduced sex ratio at birth. Exposure to air pollutants can also lead to premature birth, suggesting that inflammation within the body may affect pregnancy maintenance and fetal development. On the other hand, the effects of air pollutants carried from afar by monsoons on the sex ratio at birth in downstream areas have not been evaluated. We focused on the Goto Islands, where various air pollutants flow from the Eurasian continent. The objective of this study was to clarify the effects of the atmospheric level of each pollutant on the sex ratio at birth on the Goto Islands. METHODS: We extracted observation data of particulate matter 2.5, sulfur dioxide, oxidants, nonmethane hydrocarbons, and methane from the National Institute for Environmental Studies database. In addition, the monthly sex ratio at birth was calculated using birth data from the National Statistics Center. To evaluate the effect of substance exposure just before fertilization on the sex ratio at birth, we analyzed the relationship between the observed pollutant level and the sex ratio at birth 9 months later. A stepwise generalized linear model was used to analyze the effects of air pollutant levels on the sex ratio at birth. RESULTS: The observed values for all pollutants were significantly different between seasons, including the particulate matter 2.5 (p < 0.0001), sulfur dioxide (p = 0.0026), oxidant (p < 0.0001), nonmethane hydrocarbon (p < 0.0001), and methane (p < 0.0001) values. In the target population in the target period, the total number of births was 1835, and the sex ratio at birth was 0.967. Univariate analysis showed that the values of particulate matter 2.5 (p = 0.0157) and oxidants (p = 0.0047) correlated negatively with the sex ratio at birth. In addition, the results of multivariate analysis using the stepwise method in the model equation indicated that every 1 ppm increase in the observed OX value resulted in a 0.311 decrease in the sex ratio at birth (p = 0.0034). CONCLUSIONS: We evaluated the relationship between seasonal variations in air pollutant levels and the sex ratio at birth 9 months later on the Goto Islands. We found that an increase in oxidant levels just before and after conception may be a risk factor for a lower sex ratio at birth. Due to the previously reported vulnerability of male fetuses, females who become pregnant when air pollutant concentrations are high may be more likely to have a female baby. It is necessary to evaluate the effects of oxidants on various aspects of pregnancy and childbirth.

What can we learn from epidemiological studies on chronic boron exposure?

Boric acid and sodium borates are classified as toxic to reproduction and development under category 1B, with the hazard statement of H360FD (May damage fertility. May damage the unborn child) in the EU-CLP regulation. This classification triggered environmental and occupational epidemiology studies on boron in China, Türkiye, and Argentina. The highest mean total daily boron exposure (DBE) levels in mining areas or processing plants in China and Türkiye were 41.2 and 47.17 mg/day, respectively. These DBE levels are higher than the proposed reference doses (RfDs) for the developmental (9.6 mg B/day) and reproductive effects (20.3 mg B/day) of boron in females and males. Despite these high exposure levels in occupational settings, boron-mediated reproductive and developmental effects have not been reported. Blood (or serum) boron concentrations were also reported in these studies. The highest mean blood-boron concentration reported for the boron-exposed male workers in Türkiye is 570.6 ng B/g (ppb). This blood-boron concentration is still much lower than the blood boron concentrations corresponding to the no observed adverse effect level (NOAEL) for both developmental and reproductive effects in rats. Given the blood boron concentrations reported in current epidemiological studies, the lack of reproductive and developmental effects in humans is not surprising. Recent epidemiological studies have proven that it will not be possible to reach the critical blood boron concentrations in humans for the reproductive and developmental effects, especially in daily life.

Regional differences in the sex ratio at birth in Mexico

Objective: The sex ratio at birth, defined as males/total (M/T) approximates 0.515 but is affected by many factors. Acute and chronic stress have been shown to lower M/T, and both regional and racial differences exist. This study analysed regional differences in M/T in Mexico. Material and Methods: Live births by sex and year were available for 1994-2020. Regional births were available for 2010-2020 for five regions: North, Centre, West, East and South. Results: There were 68,423,415 births for 1994-2020 and 25,436,687 for 2010-2020 (M/T=0.5060, 95% confidence interval: 0.5058-0.5062). M/T was <0.515 (p<0.0001). Live births correlated negatively with year (p<0.0001). M/T fell for 1994-2003 then rose to 2020 (p<0.0001). M/T was highest in North followed by West, South, Centre and East (p<0.0001). Conclusion: Chronic stress with socioeconomic deprivation may reduce M/T and may explain the low M/T found in this study from Mexico.

COVID-19 induced birth sex ratio changes in England and Wales.

Background: The sex ratio at birth (male live births divided by total live births) may be a sentinel health indicator. Stressful events reduce this ratio 3-5 months later by increasing male fetal loss. This ratio can also change 9 months after major population events that are linked to an increase or decrease in the frequency of sexual intercourse at the population level, with the ratio either rising or falling respectively after the event. We postulated that the COVID-19 pandemic may have affected the ratio in England and Wales. Methods: Publicly available, monthly live birth data for England and Wales was obtained from the Office for National Statistics up to December 2020. Using time series analysis, the sex ratio at birth for 2020 (global COVID-19 onset) was predicted using data from 2012-2019. Observed and predicted values were compared. Results: From 2012-2020 there were 3,133,915 male and 2,974,115 female live births (ratio 0.5131). Three months after COVID-19 was declared pandemic (March 2020), there was a significant fall in the sex ratio at birth to 0.5100 in June 2020 which was below the 95% prediction interval of 0.5102-0.5179. Nine months after the pandemic declaration, (December 2020), there was a significant rise to 0.5171 (95% prediction interval 0.5085-0.5162). However, December 2020 had the lowest number of live births of any month from 2012-2020. Conclusions: Given that June 2020 falls within the crucial window when population stressors are known to affect the sex ratio at birth, these findings imply that the start of the COVID-19 pandemic caused population stress with notable effects on those who were already pregnant by causing a disproportionate loss of male fetuses. The finding of a higher sex ratio at birth in December 2020, i.e., 9 months after COVID-19 was declared a pandemic, could have resulted from the lockdown restrictions that initially spurred more sexual activity in a subset of the population in March 2020.

Factors influencing the sex ratio at birth in the United States from a historical perspective.

Many of the studies on the sex ratio at birth (SRB) are based on a small number of cases over a short period of time. Taking a multivariate approach to a dataset consisting of nearly 199 million birth records in the United States from 1968 to 2019, we present a detailed analysis of several possible factors that might affect the sex ratio at birth (SRB) and its patterns of variation. We found that race/ethnicity is the variable with the strongest influence on this index. Parental age, birth order and solar radiation also have a bearing on the SRB, albeit only to a moderate degree. The historical evolution of the SRB among Black and American Indian and Alaska Native populations remains unexplained.

An empirical analysis of the impact of gender inequality and sex ratios at birth on China's economic growth.

The contribution of women to China's economic growth and development cannot be overemphasized. Women play important social, economic, and productive roles in any economy. China remains one of the countries in the world with severe gender inequality and sex ratio at birth (SRB) imbalance. Severe gender inequality and disenfranchisement of girls with abnormally high sex ratios at birth reflect deep-rooted sexism and adversely affect girls' development. For China to achieve economic growth, women should not be ignored and marginalized so that they can contribute to the country's growth, but the sex ratio at birth needs to be lowered because only women can contribute to growth. Thus, this study empirically predicts an asymmetric relationship between gender inequality, sex ratio at birth and economic growth, using NARDL model over the period 1980-2020. The NARDL results show that increases in gender inequality and sex ratio at birth significantly reduce economic growth in both the short and long term, while reductions in gender inequality and sex ratio at birth significantly boost economic growth in both the short and long term. Moreover, the results show the significant contribution of female labor force participation and female education (secondary and higher education) to economic growth. However, infant mortality rate significantly reduced economic growth. Strategically, the study recommends equal opportunities for women in employment, education, health, economics, and politics to reduce gender disparities and thereby promote sustainable economic growth in China. Moreover, policymakers should introduce new population policy to stabilize the sex ratio at birth, thereby promoting China's long-term economic growth.

Trends in female-selective abortion among Asian diasporas in the United States, United Kingdom, Canada and Australia.

Preference for sons and smaller families and, in the case of China, a one-child policy, have contributed to missing girl births in India and China over the last few decades due to sex-selective abortions. Selective abortion occurs also among Indian and Chinese diaspora, but their variability and trends over time are unknown. We examined conditional sex ratio (CSR) of girl births per 1000 boy births among second or third births following earlier daughters or sons in India, China, and their diaspora in Australia, Canada, United Kingdom (UK), and United States (US) drawing upon 18.4 million birth records from census and nationally representative surveys from 1999 to 2019. Among Indian women, the CSR in 2016 for second births following a first daughter favoured boys in India (866), similar to those in diaspora in Australia (888) and Canada (882). For third births following two earlier daughters in 2016, CSRs favoured sons in Canada (520) and Australia (653) even more than in India (769). Among women in China outside the one-child restriction, CSRs in 2015 for second order births somewhat favoured more girls after a first son (1154) but more heavily favoured boys after a first daughter (561). Third-birth CSRs generally fell over time among diaspora, except among Chinese diaspora in the UK and US. In the UK, third-birth CSRs fell among Indian but not among other South Asian diasporas. Selective abortion of girls is notable among Indian diaspora, particularly at higher-order births.

COVID-19 onset reduced the sex ratio at birth in South Africa.

Background: The sex ratio at birth (defined as male/(male+female) live births) is anticipated to approximate 0.510 with a slight male excess. This ratio has been observed to decrease transiently around 3-5 months following sudden unexpected stressful events. We hypothesised that stress engendered by the onset of the COVID-19 pandemic may have caused such a decrease in South Africa 3-5 months after March 2020 since in this month, South Africa reported its first COVID-19 case, death and nationwide lockdown restrictions were instituted. Methods: We used publicly available, recorded monthly live birth data from Statistics South Africa. The most recent month for which data was available publicly was December 2020. We analysed live births for a 100-month period from September 2012 to December 2020, taking seasonality into account. Chi-squared tests were applied. Results: Over this 100-month period, there were 8,151,364 live births. The lowest recorded monthly sex ratio at birth of 0.499 was in June 2020, 3 months after March 2020. This June was the only month during this period where the sex ratio inverted i.e., fewer male live births occurred. The predicted June 2020 ratio was 0.504. The observed June 2020 decrease was statistically significant p = 0.045. Conclusions: The sex ratio at birth decreased and inverted in South Africa in June 2020, for the first time, during the most recent 100-month period. This decline occurred 3 months after the March 2020 onset of COVID-19 in South Africa. As June 2020 is within the critical window when population stressors are known to impact the sex ratio at birth, these findings suggest that the onset of the COVID-19 pandemic engendered population stress with notable effects on pregnancy and public health in South Africa. These findings have implications for future pandemic preparedness and social policy.

Cultural and Social Bias Leading to Prenatal Sex Selection: India Perspective.

Globally, 23.1 million missing female births have been documented, resulting in an imbalanced sex ratio at birth (SRB) between the late 1990s and 2017, with India accounting for almost half of this missing women population. While the country is progressively taking measures to enhance women's position in society and implementing policies toward augmenting the value of a girl child, some deeply rooted cultural and social beliefs propel a strong son preference, resulting in active daughter discrimination. The continuance of patriarchal norms and inequitable gender roles, resulting in son preference, fertility decrease, and reduction in preferred family sizes, and technical breakthroughs that allow for the identification of the sex of the fetus, is all connected to distortions in the sex ratio at birth. Son preference is a well-documented phenomenon in India, and its implications for skewed gender ratios, female feticide, and higher child mortality rates for girls have piqued researchers' and policymakers' interest. The fundamental factors of son preference as an ideology are less widely investigated. With this objective, an extensive secondary review was conducted of the socio-cultural norms and biases leading to increased prenatal sex selection in India despite the laws against it. The study findings suggest that it is imperative to emphasize the necessity for consistent and collective efforts from all stakeholders: changing the social perception of the value of girls requires collective effort and the equal participation of all stakeholders, including civil society organizations and the local community.

Conflicts and son preference: Micro-level evidence from 58 countries.

Research on the association between armed conflict and son preference has largely been based on single-country studies, often presenting descriptive patterns. This paper empirically analyzes the association between conflict and son preference using a sample of more than 1.1 million individuals from 58 countries over the period 2003-2018. We empirically show that both the incidence and intensity of conflict exposure are associated with greater son preference. Moreover, conflict-exposed individuals are likely to realise their preference for sons, as reflected in the systematically higher prevalence of sons over daughters among these individuals. To explore the aggregate effects of these findings, we conduct a cross-country analysis of sex ratios and show that history of conflict exposure plays an important role in explaining the cross-country differences in sex ratios.

Estimation and probabilistic projection of levels and trends in the sex ratio at birth in seven provinces of Nepal from 1980 to 2050: a Bayesian modeling approach.

BACKGROUND: The sex ratio at birth (SRB; ratio of male to female births) in Nepal has been reported around the normal level on the national level. However, the national SRB could mask the disparity within the country. Given the demographic and cultural heterogeneities in Nepal, it is crucial to model Nepal SRB on the subnational level. Prior studies on subnational SRB in Nepal are mostly based on reporting observed values from surveys and census, and no study has provided probabilistic projections. We aim to estimate and project SRB for the seven provinces of Nepal from 1980 to 2050 using a Bayesian modeling approach. METHODS: We compiled an extensive database on provincial SRB of Nepal, consisting 2001, 2006, 2011, and 2016 Nepal Demographic and Health Surveys and 2011 Census. We adopted a Bayesian hierarchical time series model to estimate and project the provincial SRB, with a focus on modelling the potential SRB imbalance. RESULTS: In 2016, the highest SRB is estimated in Province 5 (Lumbini Pradesh) at 1.102, corresponding to 110.2 male births per 100 female births, with a 95% credible interval (1.044, 1.127) and the lowest SRB is in Province 2 at 1.053 (1.035, 1.109). The SRB imbalance probabilities in all provinces are generally low and vary from 16% in Province 2 to 81% in Province 5 (Lumbini Pradesh). SRB imbalances are estimated to have begun at the earliest in 2001 in Province 5 (Lumbini Pradesh) with a 95% credible interval (1992, 2022) and the latest in 2017 (1998, 2040) in Province 2. We project SRB in all provinces to begin converging back to the national baseline in the mid-2030s. By 2050, the SRBs in all provinces are projected to be around the SRB baseline level. CONCLUSIONS: Our findings imply that the majority of provinces in Nepal have low risks of SRB imbalance for the period 1980-2016. However, we identify a few provinces with higher probabilities of having SRB inflation. The projected SRB is an important illustration of potential future prenatal sex discrimination and shows the need to monitor SRB in provinces with higher possibilities of SRB imbalance.

The Effect of China's Two-Child Policy on the Child Sex Ratio: Evidence From Shanghai, China.

OBJECTIVE: The bias towards males at birth has resulted in a major imbalance in the Chinese sex ratio that is often attributed to China's one-child policy. Relaxation of the one-child policy has the potential to reduce the imbalance in the sex ratio away from males. In this study, we assessed whether the bias towards males in the child sex ratio was reduced as a result of the two-child policy in China. Medical records data from one large municipal-level obstetrics hospital in Shanghai, East China. DESIGN: Matching and difference-in-differences (MDID) techniques were used to investigate the effect of the two-child policy on the imbalance in the sex ratio at birth after matching for pregnancy status and socioeconomic factors. RESULTS: Analyzing 133,358 live births suggest that the relaxation of the one-child policy had a small, but statistically significant effect in reducing the imbalance in the male to female sex ratio at birth. CONCLUSION: The results demonstrate that relaxation of the one-child policy reduced the imbalance in the male to female sex ratio at birth from 1.10 to 1.05 over the study period at one of the major obstetrics and gynecology hospitals in China.

Sex-ratio at birth in Nigeria: A demographic perspective.

The study attempts at estimating the sex-ratio at birth in Nigeria. The study focuses on demographic surveys with complete maternity histories, including some 0.50 million births. It compares results with published estimates from births in health facilities and a few data from vital registration, including some 1.13 million births. Results from demographic surveys give an estimate of about 106 boys for 100 girls. There were no significant variations by large region in the country, and no significant trend over the years (1990-2018). Published estimates provided a similar value (106.2), with somewhat lower value in health facilities (105.3), and somewhat higher values in local vital registration (106.8), and major variations among available studies. Despite uncertainty, Nigeria appears to have higher sex-ratios than most African countries, with the exception of Ethiopia, and higher values than its five neighboring countries. Reasons for these high values of the secondary sex-ratio are discussed.

The COVID-19 stress may influence on the sex ratio at birth.

The ratio of boys to girls (sex ratio) at birth (SRB) is about 1.01-1.05 in most populations and is influenced by various factors, such as maternal stress, maternal inflammation, and endocrine disruption. Male fetus is biologically weaker and more vulnerable to prenatal events than female fetuses. Hence, premature death (and consequently decline the SRB) is higher in boys than girls. The recent coronavirus disease 2019 (COVID-19) has been known to have a variety of stressful and psychological impacts. This stress may consequently enhance maternal inflammation, pregnancy complication, and fetal loss. Also, male fetuses have more adverse outcomes than female fetuses among asymptomatic pregnant women with SARS-Cov-2 infection. Inasmuch as the male fetus are more vulnerable to prenatal events and premature death, it is proposed that the SRB can decline in pregnant women following the COVID-19 stress. However, future studies are needed to define the impact of the COVID-19 on SRB rate.

Sex-ratio at birth in Nigeria: A demographic perspective

The study attempts at estimating the sex-ratio at birth in Nigeria. The study focuses on demographic surveys with complete maternity histories, including some 0.50 million births. It compares results with published estimates from births in health facilities and a few data from vital registration, including some 1.13 million births. Results from demographic surveys give an estimate of about 106 boys for 100 girls. There were no significant variations by large region in the country, and no significant trend over the years (1990-2018). Published estimates provided a similar value (106.2), with somewhat lower value in health facilities (105.3), and somewhat higher values in local vital registration (106.8), and major variations among available studies. Despite uncertainty, Nigeria appears to have higher sex-ratios than most African countries, with the exception of Ethiopia, and higher values than its five neighboring countries. Reasons for these high values of the secondary sex-ratio are discussed. (Afr J Reprod Health 2022; 26[4]: 92-97).