Age-specific prevalence of hepatitis B virus infection in young pregnant women, Hong Kong Special Administrative Region of China.

OBJECTIVE: To investigate the age-specific prevalence of hepatitis B virus (HBV) infection in young pregnant women in Hong Kong Special Administrative Region (SAR), China, and to determine whether an increase in prevalence occurs during adolescence. METHODS: HBV prevalence was quantified using data from routine antenatal screening for hepatitis B surface antigen (HBsAg) in 10 808 women aged 25 years or younger born in Hong Kong SAR and managed at a single hospital between 1998 and 2011. The effect on prevalence of maternal age, parity and birth before or after HBV vaccine availability in 1984 was assessed, using Spearman's correlation and multiple logistic regression analysis. FINDINGS: Overall, 7.5% of women were HBsAg-positive. The prevalence ranged from 2.3% to 8.4% in those aged ≤ 16 and 23 years, respectively. Women born in or after 1984 and those younger than 18 years of age were less likely to be HBsAg-positive (odds ratio, OR: 0.679; 95% confidence interval, CI: 0.578-0.797) and (OR: 0.311; 95% CI: 0.160-0.604), respectively. For women born before 1984, there was no association between HBsAg carriage and being younger than 18 years of age (OR: 0.60; 95% CI: 0.262-1.370) Logistic regression analysis showed that the prevalence of HBsAg carriage was influenced more by the woman being 18 years old or older (adjusted OR, aOR: 2.80; 95% CI: 1.46-5.47) than being born before 1984 (aOR: 1.42; 95% CI: 1.21-1.67). CONCLUSION: Immunity to HBV in young pregnant women who had been vaccinated as neonates decreased in late adolescence.

Ultrasound screening for fetal structural abnormalities performed by trained midwives in the second trimester in a low-risk population--an appraisal.

OBJECTIVE: To determine the performance of trained midwives in second trimester ultrasound screening for fetal structural abnormalities in a low-risk population. DESIGN: Retrospective study. SETTING: University Department of Obstetrics and Gynecology. POPULATION: About 13,882 women with singleton pregnancies. METHODS: The findings of routine second trimester anomaly scan performed by midwives were reviewed. Reasons for referral to maternal fetal medicine (MFM) specialists for further assessment were analyzed. MAIN OUTCOME MEASURES: The detection, false positive and false alarm rates for fetal anomalies. RESULTS: One hundred and eighty-nine pregnancies with unknown outcome were excluded from the final analysis. Overall, 617 (4.51%) women were referred to MFM specialists for further assessment, of which 470 (70.2%) were for soft markers alone and 147 (23.8%) for suspected fetal structural abnormalities. In these 13,693 fetuses with known outcome, malformed fetuses were present in 185, a prevalence of 1.35%. Of these, 115 were detected during the second trimester scan and two were detected in the third trimester. The remaining 68 malformed fetuses, most of which had minor anomalies, were identified after birth. The detection rate for a malformed fetus in second trimester scan was 62.2% (115/185) (95% CI 55.2-69.2). There were four cases of false positives and 33 cases of false alarm. CONCLUSIONS: Experienced midwives with proper training can detect the majority of major structural abnormalities. Continuous audit and quality control plays a significant role in optimizing the fetal structural examination.

Fetal nasal bone status in Chinese women undergoing first-trimester screening for trisomy 21.

OBJECTIVE: The objective of the study was to determine the likelihood ratio for trisomy 21 in Chinese fetuses with absent nasal bone (NB) at 11-14 weeks of gestation. STUDY DESIGN: The NB was classified as present or absent in 8101 chromosomally/phenotypically normal or trisomy 21 pregnancies. The effect of crown rump length (CRL), nuchal translucency (NT), maternal age, and fetal karyotype on the incidence of absent NB was examined using logistic regression. RESULTS: The NB was successfully examined in 7925 cases (97.8%). The incidence of absent NB in unaffected and trisomy 21 cases were 2.1% (164/7899) and 50% (13/26), respectively. CRL (odds ratio [OR], 0.9; 95% confidence interval [CI], 0.87-0.92), NT (OR, 1.7; 95% CI, 1.4-2.3), and trisomy 21 (OR, 22.3; 95% CI, 8.1-61) were significant independent predictors of likelihood of absent NB. Positive likelihood ratios (LR) for trisomy 21 in Chinese were lower than that of Caucasians for the equivalent CRL and NT measurements. CONCLUSION: Estimated risk for trisomy 21 in Chinese incorporating nasal bone status should use LRs derived in Chinese rather than Caucasians.

Prior abortion history and pregnancy hypertensive disorders in primiparous gravidae.

OBJECTIVES: To explore the relationship between prior abortion history with incidence of pregnancy hypertensive disorders (PHD), including gestational hypertension (GH) and pre-eclampsia (PE), to determine whether the secular increases in GH and PE in developed countries could be related in part to the decreased incidence of abortion. STUDY DESIGN: A single center retrospective cohort study on primiparous Chinese gravidae managed in 1997-2015 in our hospital. MAIN OUTCOME MEASURES: The occurrence of PHD, GH and PE with respect to the presence or otherwise of prior abortions, with the analysis stratified for risk factors that include advanced age, high body mass index (BMI), history of medical disorders, birth before 34 weeks, and maternal hepatitis B virus (HBV) infection and rubella non-immunity which have been shown to influence the occurrence of PHD in our population. RESULTS: The 23,698 (39.3%) of the 60,335 gravidae in the cohort with ≥ one prior abortion had higher incidence of advanced age, HBV infection, rubella non-immunity, and high BMI, but lower incidence of PHD, GH, PE and birth before 34 weeks gestation. The difference in the incidence of GH and PE between gravidae having one versus those with two or more abortions was minimal, and the effect of abortion on PHD was influenced by the other risk factors. On regression analysis, prior abortion reduced PHD (aRR 0.761, 95% CI 0.684-0.846), GH (aRR 0.660, 95% CI 0.563-0.773), and PE (aRR 0.857, 95% CI 0.745-0.987). CONCLUSIONS: Prior abortion reduces the subsequent development of GH and PE in primiparous women.

Soluble fms-like tyrosine kinase-1, placental growth factor and their ratio as a predictor for pre-eclampsia in East Asians.

OBJECTIVE: To assess the clinical utility of the sFlt-1:PlGF ratio rule-in/rule-out pre-eclampsia either directly or after correcting each marker for gestation and maternal weight. METHODS: This was a prospective cohort study. sFlt-1, PlGF were measured in 965 women randomized to undergo a single blood withdraw between 20 and 39 weeks of gestation. sFlt-1, PlGF and the sFlt-1:PlGF ratio temporal relationship was determined. sFlt-1 and PlGF were converted to multiples of the expected gestational median (MoM) and adjusted for maternal weight. The 90th centile of the adjusted sFlt-1MoM:PlGFMoM ratio was determined. Clinical utility of the sFlt-1:PlGF ratio (≥38) to rule in/rule-out pre-eclampsia (PE) after 20 weeks of gestation versus that of the sFlt-1MoM:PlGFMoM 90th percentile was assessed in 81 women admitted for management of antenatal hypertension. RESULTS: The sFlt-1:PlGF ratio had quadratic relationship with gestation whereas the sFlt-1MoM:PlGFMoM ratio log distribution that was Gaussian with a mean of zero and a standard deviation of 0.85 with a 90th percentile equal to 1.08. Thirty-four (42%) of the 81 women admitted for management of their antenatal hypertension had PE, 26 (76.4%) had a sFlt-1:PlGF ratio ≥ 38. Four of the remaining 8 PE affected pregnancies with sFlt-1:PlGF ratio <38 delivered within 7 days, 3 were preterm. Two of the 3 preterm PE pregnancies had sFlt-1MoM:PlGFMoM exceeding 90th percentile. CONCLUSION: The relative level of the sFlt-1 to PlGF carries prognostic value. A sFlt-1MoM:PlGFMoM ratio exceeding the 90th centile resulted in additional detection of pregnancies which developed PE compared to the conventional sFlt-1:PlGF ratio.

Maternal rubella immunity status and pre-eclampsia.

PROBLEM: To determine if maternal immune maladaptation associated with pre-eclampsia is reflected in the rubella immunity status. METHOD OF STUDY: Incidence of pre-eclampsia was compared between rubella non-immune and immune gravidae carrying a singleton pregnancy beyond 24 weeks, taking into account maternal characteristics and reported risk factors for pre-eclampsia. RESULTS: The 9870 (10.4%) rubella non-immune gravidae among the 95 024 in the cohort exhibited no difference in incidence of underlying medical disorders, but they were slightly but significantly older, shorter, heavier, and had more pre-eclampsia (OR 1.24, 95% CI 1.05-1.47) despite having fewer nulliparas. Regression analysis confirmed an overall association between rubella non-immunity with pre-eclampsia (aOR 1.27, 95% CI 1.06-1.54), which was related to multiparas (aOR 1.42, 95% CI 1.05-1.91) and carrying a male fetus (aOR 1.37, 95% CI 1.06-1.78). CONCLUSION: The association between rubella non-immunity and pre-eclampsia reflects immune maladaptation in multiparas and toward a male fetus.

Rubella seronegativity in antenatal screening - Is it influenced by the introduction of universal childhood rubella immunization?

OBJECTIVE: This study examined the impact of rubella immunization, implemented in Hong Kong in phases since 1978, on antenatal rubella serological status in Chinese women. METHODS: In a retrospective cohort study, the incidence of antenatal rubella seronegative status in our parturients managed from 1998 to 2013 was analyzed by their year-of-birth as follows: <1965 (no childhood immunization), 1965-1982 (single dose at Primary 6), and ≥1983 (two doses at age 12 months and 12 years), adjusting for other factors including age, parity, body mass index, place-of-birth status and hepatitis B surface antigen (HBsAg) status. FINDINGS: Rubella seronegativity decreased from 12.9%, 10.5%, to 9.8% respectively, and correlated inversely (P<0.001) with year-of-birth cohorts. Despite similar demographic profiles, this correlation was found only in Hong-Kong-born women (from 12.6%, 7.5% to 6.5% respectively), who also had significant lower incidences of rubella seronegativity (OR 0.73, 0.31 and 0.29 respectively) and HBsAg seropositivity (OR 1.09, 0.63 and 0.48 respectively) than China-born women. On regression analysis, rubella seronegativity was actually significantly increased following the implementation of immunization (aOR 1.20) while it was the reverse for non-residents (aOR 0.61). CONCLUSION: Although rubella seronegativity decreased with immunization, the effect was less than expected when adjusted for other risk factors.

Advanced maternal age and postpartum hemorrhage - risk factor or red herring?

OBJECTIVE: To determine the relationship between advanced maternal age (≥35 years) and incidence of postpartum hemorrhage (PPH) in singleton pregnancies managed over a 10-year period. METHOD: Retrospective cohort study comparing demographics, risk factors, complications, infant outcome, and incidence of PPH between parturients aged ≥35 and <35 years at delivery. RESULTS: Parturients aged ≥35 years (12 686/64 886 or 19.6%) had significantly increased obstetric risk factors, complications, cesarean delivery, large-for-gestational age infants, and incidence of PPH, but no difference in the attributed cause of PPH such as uterine atony, retained placenta, genital lacerations, except for multiple factors. Multivariate analysis indicated that aging was actually associated with decreased PPH, the risk decreasing progressively from those aged 25-29 years to those aged ≥40 years compared with the 20-24 years group. CONCLUSIONS: Advanced maternal age only served as a surrogate factor for PPH due to the associated increased risk factors, obstetric complications and interventions.

The force applied to successfully turn a foetus during reattempts of external cephalic version is substantially reduced when performed under spinal analgesia.

OBJECTIVE: To compare the forces exerted during external cephalic version (ECV) on the maternal abdomen between ( 1 ) the primary attempts performed without spinal analgesia (SA), which failed and ( 2 ) the subsequent reattempts performed under SA. METHODS: Patients with an uncomplicated singleton breech-presenting pregnancy suitable for ECV were recruited. During ECV, the operator wore a pair of gloves, which had thin piezo-resistive pressure sensors measuring the contact pressure between the operator's hands and maternal abdomen. For patients who had failed ECV, reattempts by the same operator was made with patients under SA, and the applied force was measured in the same manner. The profile of the exerted forces over time during each attempt was analyzed and denoted by pressure-time integral (PTI: mmHg sec). Pain score was also graded by patients using visual analogue scale. Both PTI and pain score before and after the use of SA were then compared. RESULTS: Overall, eight patients who had a failed ECV without SA underwent a reattempt with SA. All of them had successful version and the median PTI of the successful attempts under SA were lower than that of the previous failed attempts performed without SA (127 386 mmHg sec vs. 298,424 mmHg sec; p = 0.017). All of them also reported a 0 pain score, which was significantly lower than that of before (median 7.5; p = 0.016). CONCLUSIONS: SA improves the success rate of ECV as well as reduces the force required for successful version.

The impact of fetal gender on preterm birth in a southern Chinese population.

OBJECTIVE: This study was conducted to determine whether carrying a singleton male fetus increases the risk of preterm birth (PTB) in Chinese women. METHODS: A retrospective cohort study was conducted on women with singleton pregnancies and delivered in our hospital. Maternal characteristics, pregnancy outcome, and incidence of PTB, were compared between women carrying a male versus a female fetus. The independent effect of a male fetus on PTB was examined with multiple logistic regression analysis adjusting for the other confounding factors identified. RESULTS: There were significant differences in maternal and infant characteristics between women with a male versus a female fetus. Despite similar or lower incidences of complications and labor induction, women with a male fetus had increased birth <37 weeks (7.0% versus 6.2%, p

Use of hemostatic gel in postpartum hemorrhage due to placenta previa.

BACKGROUND: Hemostasis for placenta previa is notoriously difficult because of the poor contractility of the lower segment. A hemostatic gel offers a new type of hemostatic matrix, which may have advantages. CASE: A 35-year-old woman had a postpartum hemorrhage despite the use of uterotonics 2 hours after cesarean delivery for major placenta previa. On relaparotomy, heavy oozing from the placental site was found. Difficult accessibility and profuse bleeding prompted the consideration of alternative treatment with the topical application of hemostatic gel over the lower segment, which achieved hemostasis within minutes. CONCLUSION: Hemostatic gel is easily applicable and provides quick and effective hemostatic control in the lower segment, where surgical intervention may be difficult.

Effect of long-term storage on placental growth factor and fms-like tyrosine kinase 1 measurements in samples from pregnant women.

OBJECTIVE: To assess the effect of storage time on the stability of placental growth factor (PlGF) and fms-like tyrosine kinase 1 (sFlt-1) levels in frozen serum samples from pregnant women. METHODS: This is a matched case-control study using fresh and stored serum samples collected at 6, 12, 18, 24, 30 and 36 months prior to the collection of the fresh samples and frozen at -80°C. Forty-eight samples from each of the seven time-groups were matched for non-smoking Chinese, maternal weight, singleton-term pregnancy without major obstetric complications and extracted for PlGF and sFlt-1 assays. Multivariate analysis was performed to assess residual effects of the case-matching procedure. ANOVA was used to assess the effects of storage time. RESULTS: Multivariate analysis of the 336 samples indicated that log(10)PlGF was positively correlated with parity (p=0.014) and gestational age (p=0.029), while log(10)sFlt-1 was inversely correlated with parity (p=0.018). After correcting for the residual effect of gestation and parity, ANOVA showed no significant difference in PlGF and sFlt-1 levels between the fresh samples and all stored samples (p=0.410 and p=0.158, respectively). CONCLUSIONS: Serum PlGF and sFlt-1 levels are stable for at least 3 years when stored at -80°C. Parity is an independent factor of PlGF and sFlt-1 levels. PlGF levels are lower and sFlt-1 levels are higher in nulliparous women compared to multiparous.

Randomised trial of assigned mode of delivery after a previous cesarean section--impact on maternal psychological dynamics.

OBJECTIVE: This randomised trial was designed to study the psychological status and morbidity during and after delivery among women with a previous cesarean section (CS) who were randomised to planned vaginal birth (VBAC) or planned CS. METHODS: Two hundred and ninety-eight women with one previous lower segment CS were randomised to either planned VBAC or planned CS. Women were asked to complete psychometric scales during their pregnancy till 6 months after confinement. The primary outcome studied was the differences in psychometric scores between the two study groups. RESULTS: There were no differences in anxiety, depression, psychological well-being or satisfaction scores between the two groups. Significantly more women in planned VBAC (27/123) requested to change to elective CS, compared to those who were randomised to planned CS (15/135) initially requested to change to planned VBAC (OR: 2.25; 95% CI: 1.13-4.47). Subgroup analyses showed that women who changed from planned CS to VBAC had lower satisfaction at delivery [Client Satisfaction Score: 24.0 (23.0-24.3), 23.0 (22.0-24.0); p=0.009] compared to women who did not change their plan for elective CS. CONCLUSIONS: The planned mode of delivery, either elective CS or VBAC, in pregnant women who had one previous CS did not influence the psychological dynamic during the course of or after the pregnancy. VBAC was not associated with higher psychological morbidity and therefore should be encouraged.

First trimester combined screening for Trisomy 21 in Hong Kong: outcome of the first 10,000 cases.

OBJECTIVE: To examine the effectiveness of first trimester fetal Trisomy 21 (T21) screening using a combination of maternal age, nuchal translucency, maternal serum levels of free beta-hCG and PAPP-A in a predominantly Chinese population in Hong Kong. METHODS: Consecutive women who underwent the combined screening for T21 between 11 and 13 + 6 weeks of gestation between 2003 and 2007 were recruited. Risk of T21 was calculated using Fetal Medicine Foundation algorithm and karyotyping was advised when the risk was 1:300 or above. All women were followed up for pregnancy and fetal outcome. RESULTS: 10,363 fetuses underwent screening. 99% of the women were Chinese and 27.4% were at or above 35 years old. 618 fetuses were screened positive (5.9%), which included 31 cases of T21, 14 cases of T18, 7 cases of T13, 10 cases of 45XO and 7 cases of other chromosomal abnormalities. Among the 9745 screened negative fetuses all but 50 (0.5%) had a known outcome, which included three T21 and four other chromosomal abnormalities. All were subsequently identified at the morphology scan except for one case of T21. The detection rate and false positive rates for T21 were 91.2% and 5.4%, respectively and the positive predictive value for all chromosomal abnormalities was 1 in 9. CONCLUSIONS: Combined screening for T21 is highly effective among Chinese women. Training, quality control, regular auditing and follow up are essential to maintain screening standards.

Variation of force applied during external cephalic version with different patients' characteristic and outcome of version.

BACKGROUND: To compare the degree of force applied during external cephalic version, between different patients' characteristic and outcomes of version. METHODS: It is a prospective observational study in a cohort of patients undergoing external cephalic version at or above 36 weeks of gestation. During external cephalic version, the operator wore a pair of pressure-sensing gloves which had ultra-thin piezo-resistive pressure sensors positioned on the palmer surface. Readings from each of the sensors were recorded in real time throughout each version attempt and analyzed by a computer program. The pressure exerted on individual sensors over time, the pressure-time integral (PTI; mmHg s), was calculated for each sensor from the start to the end of each version attempted. The degree of force applied for each attempt (PTI-A) was represented by the sum of pressure-time integrals across all sensors. PTI-A was analyzed in relation to different patients' characteristics and outcome of version. RESULTS: Ninety-two patients were recruited, 73% of whom had a successful external cephalic version. The median PTI-A of the successful attempt in women who completed version after 1 and 2 attempts were 17,180 and 17,736 mmHg s, respectively. They were significantly lower than that of the women who required 3 or more attempts for a successful version (32,351 mmHg s), as well as the highest PTI-A among all attempts received by women who finally had a failed version (31,638 mmHg s) (p <0.05, Kruskal-Wallis Test and Dunn test). Within the same subject, there was no difference in PTI-A between the successful attempt and the preceding failed attempt, suggesting that the failure may not be due to insufficient force but rather to inefficient application of the force. Uterine tone was found to be the only clinical variable that was significantly associated with the degree of applied force during a version (p < 0.05). A tenser uterus was associated with a stronger applied force. CONCLUSION: The degree of force required for a successful version is highly variable, being lowest when version can be completed within 2 attempts, but doubled when 3 or more attempts are required. Failure of version is usually not due to inadequate force but inefficient application of force. Uterine tone is significantly related to the degree of applied force, with stronger force being exerted when the uterus is tense.