Interpregnancy interval and adverse birth outcomes: a population-based cohort study of twins.

BACKGROUND: To investigate associations between interpregnancy intervals (IPIs) and adverse birth outcomes in twin pregnancies. METHODS: This retrospective cohort study of 9,867 twin pregnancies in Western Australia from 1980-2015. Relative Risks (RRs) were estimated for the interval prior to the pregnancy (IPI) as the exposure and after the pregnancy as a negative control exposure for preterm birth (< 37 weeks), early preterm birth (< 34 weeks), small for gestational age (SGA: < 10th percentile of birth weight by sex and gestational age) and low birth weight (LBW: birthweight < 2,500 g). RESULTS: Relative to IPIs of 18-23 months, IPIs of < 6 months were associated with a higher risk of early preterm birth (aRR 1.41, 95% CI 1.08-1.83) and LBW for at least one twin (aRR 1.16, 95% CI 1.06-1.28). IPIs of 6-11 months were associated with a higher risk of SGA (aRR 1.24, 95% CI 1.01-1.54) and LBW for at least one twin (aRR 1.09, 95% CI 1.01-1.19). IPIs of 60-119 months and ≥ 120 months were associated with an increased risk of preterm birth (RR 1.12, 95% CI 1.03-1.22; and (aRR 1.25, 95% CI 1.10-1.41, respectively), and LBW for at least one twin (aRR 1.17, 95% CI 1.08-1.28; and aRR 1.20, 95% CI 1.05-1.36, respectively). IPIs of ≥ 120 months were also associated with an increased risk of early preterm birth (aRR 1.42, 95% CI 1.01-2.00). After negative control analysis, IPIs ≥ 120 months remained associated with early preterm birth and LBW. CONCLUSION: Evidence for adverse associations with twin birth outcomes was strongest for long IPIs.

Coverage of immediate postpartum long-acting reversible contraception has improved birth intervals for at-risk populations.

BACKGROUND: In 2012, South Carolina revised the Medicaid policy to cover reimbursement for immediate postpartum long-acting reversible contraception. Immediate postpartum long-acting reversible contraception may improve health outcomes for populations at risk with a subsequent short-interval pregnancy. OBJECTIVES: We examined the impact of the Medicaid policy change on the initiation of long-acting and reversible contraception (immediate postpartum and postpartum) within key populations. We determined whether immediate postpartum long-acting and reversible contraception use varied by adequate prenatal care (>7 visits), metropolitan location, and medical comorbidities. We also tested the association of immediate postpartum and postpartum long-acting, reversible contraception on interpregnancy interval of less than 18 months. STUDY DESIGN: We conducted a historical cohort study of live births among Medicaid recipients in South Carolina between 2010 and 2017, 2 years before and 5 years after the policy change. We used birth certificate data linked with Medicaid claims. Our primary outcome was immediate postpartum long-acting and reversible contraception, and our secondary outcome was short interpregnancy interval. We characterize trends in long-acting and reversible contraception use and interpregnancy interval over the study period. We used logistic regression models to test the association of key factors (rural, inadequate prenatal care, and medical comorbidities) with immediate and outpatient postpartum long-acting and reversible contraception following the policy change and to test the association of immediate postpartum and postpartum long-acting and reversible contraception with short interpregnancy interval. RESULTS: Our sample included 187,438 births to 145,973 women. Overall, 44.7% of the sample was white, with a mean age of 25.0 years. A majority of the sample (61.5%) was multiparous and resided in metropolitan areas (79.5%). The odds of receipt of immediate postpartum long-acting and reversible contraception use increased after the policy change (adjusted odds ratio, 1.39, 95% confidence interval, 1.34-1.43). Women with inadequate prenatal care (adjusted odds ratio, 1.50, 95% confidence interval, 1.31-1.71) and medically complex pregnancies had higher odds of receipt of immediate postpartum long-acting and reversible contraception following the policy change (adjusted odds ratio, 1.47, 95% confidence interval, 1.29-1.67) compared with women with adequate prenatal care and normal pregnancies. Women residing in rural areas were less likely to receive immediate postpartum long-acting and reversible contraception (adjusted odds ratio, 0.36, 95% confidence interval, 0.30-0.44) than women in metropolitan areas. Utilization of immediate postpartum long-acting and reversible contraception was associated with a decreased odds of a subsequent short interpregnancy interval (adjusted odds ratio, 0.62, 95% confidence interval, 0.44-0.89). CONCLUSION: Women at risk of a subsequent pregnancy and complications (inadequate prenatal care and medical comorbidities) are more likely to receive immediate postpartum long-acting and reversible contraception following the policy change. Efforts are needed to improve access in rural areas.

Interpregnancy intervals and perinatal and child health in Sweden: A comparison within families and across social groups.

A large body of research has shown that children born after especially short or long birth intervals experience an elevated risk of poor perinatal outcomes, but recent work suggests this may be explained by confounding by unobserved family characteristics. We use Swedish population data on cohorts born 1981-2010 and sibling fixed effects to examine whether the length of the birth interval preceding the index child influences the risk of preterm birth, low birth weight, and hospitalization during childhood. We also present analyses stratified by salient social characteristics, such as maternal educational level and maternal country of birth. We find few effects of birth intervals on our outcomes, except for very short intervals (less than seven months) and very long intervals (>60 months). We find few differences in the patterns by maternal educational level or maternal country of origin after stratifying by the mother's highest educational attainment.

Postpartum Contraception and Interpregnancy Intervals Among Adolescent Mothers Accessing Public Services in California.

Objective To determine the association of age at index birth with postpartum contraceptive use and optimal interpregnancy interval (IPI, defined as delivery to next pregnancy >18 months), controlling for provider type and client demographics among adolescent mothers who have repeat pregnancies. Methods California's 2008 birth records were linked to California's Medi-Cal and Family PACT claims data to identify 26,393 women with repeat births between 2002 and 2008, whose index birth occurred as an adolescent, and who received publicly-funded services within 18 months after the index birth. Multivariable regression analyses were conducted to examine the relationship between timing of contraception provision and interpregnancy intervals, adjusting for socio-demographic factors. Results Seventy-eight percent of adolescent women did not receive contraception at their first postpartum visit, and twenty-eight percent of adolescent women never received contraception from a Family PACT or Medi-Cal provider. Adolescents who were older at their index birth had lower rates of optimal IPIs. Native American, Asian-Pacific Islander and Latina women had lower rates of optimal IPIs compared to white women. Compared to those using only barrier methods, adolescent women receiving highly effective contraceptive methods had a 4.25 times higher odds of having an optimal IPI than those receiving hormonal methods (OR 2.10), or using no method (OR 0.70). Conclusion Effective postpartum contraceptive use and being a Family PACT provider were associated with optimal birth spacing among adolescent mothers, yet racial and ethnic disparities persisted. A missed opportunity was the provision of contraception at the first postpartum visit. Providers should aim to remove barriers to initiation of contraception at this visit.

Interpregnancy interval and perinatal outcomes across Latin America from 1990 to 2009: a large multi-country study.

OBJECTIVE: To determine the relationship of interpregnancy interval with maternal and offspring outcomes. DESIGN: Retrospective study with data from the Perinatal Information System database of the Latin American Centre for Perinatology and Human Development, Uruguay. SETTING: Latin America, 1990-2009. POPULATION: A cohort of 894 476 women delivering singleton infants. METHODS: During 1990-2009 the Perinatal Information System database of the Latin American Centre for Perinatology identified 894 476 women with defined interpregnancy intervals: i.e. the time elapsed between the date of the previous delivery and the first day of the last normal menstrual period for the index pregnancy. Using the interval 12-23 months as the reference category, multiple logistic regression estimated adjusted odds ratios (aORs) with 95% confidence intervals (95% CIs) of the association between various interval lengths and maternal and offspring outcomes. MAIN OUTCOME MEASURES: Maternal death, pre-eclampsia, eclampsia, puerperal infection, fetal death, neonatal death, preterm birth, and low birthweight. RESULTS: In the reference interval there was 0.05% maternal death, 1.00% postpartum haemorrhage, 2.80% pre-eclampsia, 0.15% eclampsia, 0.28% puerperal infection, 3.45% fetal death, 0.68% neonatal death, 12.33% preterm birth, and 9.73% low birthweight. Longer intervals had increased odds of pre-eclampsia (>72 months), fetal death (>108-119 months), and low birthweight (96-107 months). Short intervals of <12 months had increased odds of pre-eclampsia (aOR 0.80; 95% CI 0.76-0.85), neonatal death (aOR 1.18; 95% CI 1.08-1.28), and preterm birth (aOR 1.16; 95% CI 1.11-1.21). Statistically, the interval had no relationship with maternal death, eclampsia, and puerperal infection. CONCLUSIONS: A short interpregnancy interval of <12 months is associated with pre-eclampsia, neonatal mortality, and preterm birth, but not with other maternal or offspring outcomes. Longer intervals of >72 months are associated with pre-eclampsia, fetal death, and low birthweight, but not with other maternal or offspring outcomes. TWEETABLE ABSTRACT: A short interpregnancy interval of <12 months is associated with neonatal mortality and preterm birth.

Interpregnancy intervals and behavioural outcomes in children: A population-based longitudinal study.

BACKGROUND: While the physical health consequence of short interpregnancy intervals (IPIs) is well documented, its mental health impact is not well explored. This study aimed to examine the associations between IPIs and behavioural outcomes in children born following the interval at four developmental time points between ages 7 and 16. METHODS: Our study sample comprised participants in the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort, an ongoing population-based longitudinal birth cohort in Bristol, Avon, United Kingdom. Behavioural problems, including total behavioural difficulties, hyperactivity, emotional symptoms, conduct problems, peer-problems, and problems of pro-social behaviour, were assessed using the Strengths and Difficulties Questionnaire (SDQ). Over 2300 mothers and their singleton children were included in this study. Generalized Estimating Equations (GEE) were used to estimate odds ratios for the associations. RESULTS: Children born to mothers with short IPI (<6 months) were 1.54 (95%CI: 1.12-2.11), 1.42 (95% CI: 1.12-1.81) and 1.37 (95%CI: 1.04-1.79) times more likely to have total behavioural difficulties, conduct problems and hyperactivity/inattention problems across the child's age, respectively, compared with children of mothers with IPIs of 18-23 months. We found no evidence of associations between short IPI (<6 months) and emotional symptoms, peer-relationship problems and pro-social behaviour problems. CONCLUSION: Short IPI (<6 months) was associated with externalising (conduct and hyperactivity/inattention) but not internalising (emotional and peer-relationship problems) problems. Further studies are needed to confirm this association and elucidate the underlying mechanisms.

Hyperemesis Gravidarum: Risk of Recurrence in Subsequent Pregnancies.

This study aimed to examine whether the recurrence risk of hyperemesis gravidarum (HG) is modified by the timing of diagnosis, the severity of illness, and interpregnancy interval. The Kaiser Permanente Southern California 1998-2020 longitudinally linked medical records were used to examine the recurrence risk of HG in the first two (n = 93,444) and first three (n = 17,492) successive pregnancies. The timing of diagnosis- and the severity of illness-specific recurrence risks were examined by estimating the adjusted relative risks (aRR). The risks of HG in the second pregnancy among patients with and without previous HG were 23.8% and 3.4%, respectively (aRR: 8.20; 95% confidence interval [CI]: 7.52, 8.94). The recurrence risk persisted regardless of the trimester at diagnosis and the gestational age of delivery in the first pregnancy. The recurrence risk was greater for patients with metabolic disturbances requiring in-hospital treatment (30.0%) than those managed on an outpatient basis (18.6%) in the first pregnancy (aRR: 10.84 95% CI: 9.66, 12.16). Although Asian/Pacific Islander (RR = 12.9) and White (RR = 8.9) patients had higher HG recurrence risk regardless of the gestational age at delivery in the first pregnancy, all patients had significant recurrence risk only if their first pregnancy was delivered after 32 weeks of gestation. African American patients had the highest recurrence rate (34.4%). HG recurrence risk was unaffected by interpregnancy interval and correlated with the number of previous pregnancies complicated by HG. There is an increased recurrence risk of HG in subsequent pregnancies that is influenced by race/ethnicity and gestational age at delivery. The number of pregnancies complicated by HG synergistically adds to the recurrence risk.

Examining the association between short interpregnancy interval births and the type and timing of postpartum long acting reversible contraception.

OBJECTIVE: To determine whether the type (intrauterine device or implant) or timing (immediately postpartum vs interval) of postpartum long-acting reversible contraception was associated with a reduction in short interpregnancy interval births. STUDY DESIGN: We conducted a retrospective cohort study using linked Medicaid claims and birth certificate data from Oregon and South Carolina, 2010 to 2018. Our primary outcome was short interpregnancy interval, defined as repeat pregnancy within 18 months of the index delivery. We determined postpartum contraceptive method and timing of receipt. To assess the association of timing of long acting reversible contraception with short interpregnancy interval, we calculated adjusted probabilities from a logistic regression model incorporating covariate balanced propensity score weights, sociodemographic factors, and clustered at the woman-level. RESULTS: Our study sample included 121,422 births to 97,084 individuals who had more than 1 birth during the study period; 41% had a short interpregnancy interval. A majority of individuals had not received any contraception by 6 months postpartum (68.6%). Overall, 15,477 individuals used long acting reversible contraception postpartum, with the majority receiving interval rather than immediate postpartum long acting reversible contraception (92.9% vs 7.1%). In multivariable analyses, both immediate postpartum (23.0%, 95% CI: 20.5%-25.8%) and interval long acting reversible contraception (15.2%, 95% CI: 14.4%-16.1%) are associated with a lower probability of short interpregnancy interval than short acting methods (42.1%, 95% CI: 41.2%-43.0%). CONCLUSION: Compared to short-acting methods, receipt of both immediate postpartum and interval long-acting reversible contraception is associated with lower probabilities of a subsequent short interpregnancy interval. IMPLICATIONS: All long acting, reversible contraception, whether placed immediately postpartum or on an interval basis, was associated with a significantly lower probability of a short interpregnancy interval than short acting or no contraceptive method.

Factors influencing women's decisions about pregnancy spacing: Findings from a focus group discussion study.

OBJECTIVES: Very short interpregnancy intervals are associated with negative health outcomes for mothers and children, and pregnancies with very short interpregnancy intervals are more likely to be unintended than pregnancies that are more widely spaced. The objective of this study was to improve understanding of women's motivations regarding pregnancy spacing. METHODS: In 2017, we conducted 8 focus group discussions with 49 English- and Spanish-speaking postpartum women in central North Carolina. The groups explored participants' preferences for birth spacing and factors that influenced their decisions. We recorded, transcribed, and coded the discussions and analyzed these data for core themes. RESULTS: Participants' ideas about when and whether to have more children were fluid-some had specific ideas during pregnancy or after delivery that changed over time; others had no definite plans. The primary reason for close birth spacing was to promote their children's having a closer relationship. Reasons for wider spacing included recovery from the previous pregnancy, challenges related to having 2 babies concurrently, and desire to wait for more favorable life circumstances. Participants did not mention health risks to children of short interpregnancy intervals and said that no health care providers discussed these risks with them. They had mixed perspectives about whether this information would influence their own child-spacing preferences but agreed that it should be shared with women to promote informed decision-making. CONCLUSION: This study adds to limited research regarding the factors that women consider when determining pregnancy spacing. Better understanding of women's motivations can help inform counseling to help women achieve their desired pregnancy spacing.

Effect of interpregnancy interval on gestational diabetes: a retrospective matched cohort study.

PURPOSE: To examine the association between interpregnancy interval (IPI) and gestational diabetes using both within-mother and between-mother comparisons. METHODS: A retrospective cohort study of 103,909 women who delivered three or more consecutive singleton births (n = 358,046) between 1 January 1980 and 31 December 2015 in Western Australia. The association between IPI and gestational diabetes was estimated using conditional logistic regression, matching pregnancies to the same mother and adjusted for factors that vary within-mother across pregnancies. For comparison with previous studies, we also applied unmatched logistic regression (between-mother analysis). RESULTS: The conventional between-mother analysis resulted in adjusted odds ratios (aOR) of 1.13 (95% CI, 1.06-1.21) for intervals of 24-59 months and 1.51 (95% CI, 1.33-1.70) for intervals of 120 or more months, compared with IPI of 18-23 months. In addition, short IPIs were associated with lower odds of gestational diabetes with (aOR: 0.89; 95% CI, 0.82-0.97) for 6-11 months and (aOR: 0.92; 95% CI, 0.85-0.99) for 12-17-month. In comparison, the adjusted within-mother matched analyses showed no statistically significant association between IPIs and gestational diabetes. All effect estimates were attenuated using the within-mother matched model. CONCLUSION: Our findings do not support the hypothesis that short IPI (<6 months) increases the risk of gestational diabetes and suggest that observed associations in previous research might be attributable to confounders that vary between mothers.

Unintended pregnancy and interpregnancy interval by maternal age, National Survey of Family Growth.

BACKGROUND: The relationship between unintended pregnancy and interpregnancy interval (IPI) across maternal age is not clear. METHODS: Using data from the National Survey of Family Growth, we estimated the percentages of pregnancies that were unintended among IPI groups (<6, 6-11, 12-17, 18-23, 24+ months) by maternal age at last live birth (15-19, 20-24, 25-29, 30-44 years). RESULTS: Approximately 40% of pregnancies were unintended and 36% followed an IPI<18 months. Within each maternal age group, the percentage of pregnancies that were unintended decreased as IPI increased. CONCLUSION: Unintended pregnancies are associated with shorter IPI across the reproductive age spectrum.

Intimate partner violence and pregnancy spacing: results from a meta-analysis of individual participant time-to-event data from 29 low-and-middle-income countries.

INTRODUCTION: Inadequately spaced pregnancies, defined as pregnancies fewer than 18 months apart, are linked to maternal, infant, and child morbidity and mortality, and adverse social, educational and economic outcomes in later life for women and children. Quantifying the relation between intimate partner violence (IPV) and women's ability to space and time their pregnancies is an important part of understanding the burden of disease related to IPV. METHODS: We applied Cox proportional hazards models to monthly data from the Demographic and Health Surveys' Reproductive Health Calendar to compare interpregnancy intervals for women who experienced physical, sexual and/or emotional IPV in 29 countries. We conducted a one-stage meta-analysis to identify the periods when women who experienced IPV were at the highest risk of unintended and incident pregnancy, and a two-stage meta-analysis to explore cross-country variations in the magnitude of the relation between women's experience of IPV and pregnancy spacing. RESULTS: For the one-stage analysis, considering 52 959 incident pregnancies from 90 446 women, which represented 232 394 person-years at risk, women's experience of IPV was associated with a 51% increase in the risk of pregnancy (95% CI 1.38 to 1.66), although this association decreased over time. When limiting our inference to unintended pregnancies that resulted in live births, women's experience of IPV was associated with a 30% increase in the risk of unintended pregnancy (95% CI 1.25 to 1.34; n=13 541 pregnancies, 92 848 women, 310 319 person-years at risk). In the two-stage meta-analyses, women's experience of IPV was associated with a 13% increase in the probability of incident pregnancy (95% CI 1.07 to 1.20) and a 28% increase in the likelihood of unintended pregnancy (95% CI 1.19 to 1.38). CONCLUSIONS: Across countries, women's experience of IPV is associated with a reduction in time between pregnancies and an increase in the risk of unintended pregnancy; the magnitude of this effect varied by country and over time.

Short interpregnancy intervals, maternal folate levels, and infants born small for gestational age: a preliminary study in a Canadian supplement-using population.

Short interpregnancy intervals (SIPI) have been associated with increased risks for adverse neonatal outcomes including preterm delivery and infants small for gestational age (SGA). It has been suggested that mechanistically, adverse neonatal outcomes after SIPI arise due to insufficient recovery of depleted maternal folate levels prior to the second pregnancy. However, empirical data are lacking regarding physiological folate levels in pregnant women with SIPI and relationships between quantified physiological folate levels and outcomes like SGA. Therefore, we sought to test 2 hypotheses, specifically that compared with controls women with SIPI would: (i) have lower red blood cell folate (RBCF) levels and (ii) be more likely to have SGA infants (defined as <10th percentile). Using data collected in British Columbia, Canada, for a larger study on perinatal psychopathology, we documented supplementation use and compared prenatal RBCF levels and proportion of SGA infants between women with SIPI (second child conceived ≤24 months after previous birth, n = 26) and matched controls (no previous pregnancies, or >24 months between pregnancies, n = 52). There were no significant differences in either mean RBCF levels (Welch's t test, p = 0.7) or proportion of SGA infants (Fisher's exact test, p = 0.7) between women with SIPI and matched controls. We report the first data about RBCF levels in the context of SIPI. If confirmed, our finding of no relationship between these variables in this population suggests that continued folic acid supplementation following an initial pregnancy mitigates folate depletion. We found no relationship between SIPI and SGA.

Missed opportunities for family planning: an analysis of pregnancy risk and contraceptive method use among postpartum women in 21 low- and middle-income countries.

OBJECTIVES: To analyze data from recent Demographic and Health Surveys (DHS) conducted in 21 low- and middle-income countries (LMICs) to examine patterns of interpregnancy intervals, unmet need, pregnancy risk and family planning method use and method mix among women 0-23 months postpartum. STUDY DESIGN: Secondary analysis of postpartum women aged 15-49 years in 22 DHS surveys from 21 LMICs conducted between 2005 and 2012. We applied an adapted unmet need definition for postpartum women to look at prospective fertility preferences. We also constructed a new composite pregnancy risk indicator for postpartum women who have been sexually active since their last birth. RESULTS: In 9 of 22 surveys, 50% or more of nonfirst births occur at interpregnancy intervals that are too short. Overall prospective unmet need for family planning by postpartum women has not changed demonstrably since a 2001 analysis and is universally high: 61% of all postpartum women across the 21 countries have an unmet need for family planning. In 10 of 22 surveys, pregnancy risk rises steadily throughout the 2 years after birth. In the remaining 12 surveys, the risk of pregnancy peaks at 6-11 months after birth. Even when postpartum women are using family planning, they rely overwhelmingly on short-acting methods (51-96% in 21 of 22 surveys). CONCLUSION: Our approach of estimating pregnancy risk by postpartum timing confirms a high probability for pregnancies to be less than optimally spaced within 2 years of a prior birth and suggests that special consideration is needed to effectively reach this population with the right messages and services. IMPLICATIONS: Using recent, multicountry data for women within 2 years postpartum in LMICs, this paper updates existing estimates of high prospective unmet need for family planning and presents a new composite pregnancy risk analysis based on postpartum women's actual practices to demonstrate the magnitude of missed opportunities for programmatic intervention for the postpartum population.