Impact of Maternal BMI on Rubella Nonimmunity at Antenatal Screening

OBJECTIVE

The aim of this study was to examine the relationship between BMI and the incidence of rubella nonimmunity among pregnant women with regard to the World Health Organization categories.

METHODS

This was a retrospective cohort study of 117,063 eligible gravidas, managed between 1998 and 2015 in a university hospital of Hong Kong, China. BMI at antenatal booking was banded using the following World Health Organization definitions: < 18.5 kg/m² , 18.5 to 24.9 kg/m² , 25.0 to 29.9 kg/m² , and ≥30.0 kg/m² . Maternal rubella nonimmunity status by BMI was assessed. Incidence rates were also assessed after adjusting for maternal advanced age, short stature < 151 cm, mothers' birthplace, and postobstetric history covariates.

RESULTS

Rubella nonimmunity incidence increased as the BMI increased (P < 0.001). Gravidas with high BMI were more likely to be nonimmune if born in Hong Kong (odds ratio [OR], 1.234; 95% CI: 1.159-1.315; P < 0.001) compared with those born outside of Hong Kong (OR, 1.066; 95% CI: 0.997-1.141; P = 0.063). After adjusting for covariates, women with BMI ≥ 25 kg/m² had 1.127 (P < 0.001; 95% CI: 1.074-1.182) greater odds of being nonimmune.

CONCLUSIONS

High maternal BMI (≥ 25.0 kg/m² ) is associated with reduced rubella immunity, an effect confined to gravidas with almost complete vaccine coverage in childhood.

Pre-Induction Transperineal Ultrasound Assessment for the Prediction of Labor Outcome

OBJECTIVE

To examine (1) the concordance of manual and automated para-symphyseal angle of progression (psAOP) measurements, (2) the repeatability of psAOP, head-symphysis distance, head-perineum distance, and sonographic cervical dilatation, and (3) the value of transperineal ultrasound (TPU) in predicting induction of labor (IOL) outcome.

METHODS

We performed a prospective study in 308 women with singleton pregnancies undergoing IOL at term. Logistic regression analysis was used to determine which maternal factors, Bishop score, method of IOL, and TPU parameters were significant predictors of cesarean section (CS) and CS due to no progress (CS-NP).

RESULTS

There was vaginal delivery in 225 (83.0%) and CS in 46 (17.0%) cases. The intra-class correlation coefficient between manual and automated psAOP was 0.866, but automated psAOP was 4.6° wider than manual measurement. All TPU parameters had an inter-observer intra-class correlation coefficient > 0.800. Significant independent prediction of CS and CS-NP was provided by maternal factors, previous vaginal delivery, and psAOP. There was no improvement in area under the receiver-operating characteristic curve with the addition of psAOP to maternal factors.

CONCLUSIONS

All TPU parameters are reproducible. Comparing the three TPU parameters for fetal head station, only psAOP is a significant independent predictor of CS; however, it is unlikely to be useful in predicting IOL outcome.

Impact of replacing Chinese ethnicity-specific fetal biometry charts with the INTERGROWTH-21(st) standard

OBJECTIVE

To assess the impact of adopting the INTERGROWTH-21(st) biometry standards in a Chinese population.

DESIGN

Retrospective cohort study.

SETTING

A teaching hospital in Hong Kong.

POPULATION

A total of 10 527 Chinese women with a singleton pregnancy having a second- or third-trimester fetal anomaly or growth scan between January 2009 and June 2014.

METHODS

Z-scores were derived for fetal abdominal circumference (AC), head circumference (HC), and femur length (FL) using the INTERGROWTH-21(st) and Chinese biometry standards. Pregnancies with aneuploidy, structural or skeletal abnormalities, or that developed pre-eclampsia were excluded. Z-scores were stratified as <2.5th, <5th, <10th, >90th, >95th, or >97.5th percentile. Birthweight centile, adjusted for gestation and gender, was categorised as ≤3rd, 3rd to ≤5th, 5th to ≤10th, and >10th. Pairwise comparison and the McNemar test were performed to assess biometry Z-score differences and concordance between the INTERGROWTH-21(st) and Chinese standards.

MAIN OUTCOME MEASURES

The sensitivity of both the local and INTERGROWTH-21(st) AC standards to identify pregnancies that were small-for-gestational-age (SGA) was assessed.

RESULTS

INTERGROWTH-21(st) AC, HC, and FL Z-scores were significantly lower than those obtained using our local reference for AC, HC, and FL (P < 0.0001 for all). The proportion of fetuses with biometry in the <2.5th, <5th, <10th, >90th, >95th, or >97.5th percentiles was statistically significant (P < 0.01 for all). A total of 1224 (15.5%) of the scans at 18-22 weeks of gestation had AC, HC, or FL below the 3rd percentile of the INTERGROWTH-21(st) standard.

CONCLUSIONS

Adopting the INTERGROWTH-21(st) standard would lead to a significant number of fetuses being at risk of misdiagnosis for small fetal size, particularly when using HC and FL measures.

TWEETABLE ABSTRACT

INTERGROWTH-21(st) biometry assessment in Chinese leads to fetuses being at risk of misdiagnosis of small fetal size.

Prospective assessment of INTERGROWTH-21st and World Health Organization estimated fetal weight reference curves

OBJECTIVES

To assess the suitability of the new INTERGROWTH-21^st and World Health Organization (WHO) estimated fetal weight (EFW) references in a Southern Chinese population. A secondary aim was to determine the accuracy of EFW by assessing the difference between EFW and actual birth weight.

METHODS

This was a prospective cross-sectional cohort study. Viable singleton pregnancies at 11-13 weeks' gestation were recruited to undergo a single standardized fetal biometric scan after 20 weeks. The gestational age at which the scan was performed was allocated randomly at the time of recruitment. EFW was predicted using both the Hadlock and INTERGROWTH-21^st weight estimation model formulae. Population-specific EFW references were constructed. Z-scores were used to compare these references against the INTERGROWTH-21^st and WHO international size references. Gestational-age-adjusted projection was used to assess the difference between EFW on the day of delivery and birth weight for fetuses having biometry scans ≥ 34 weeks.

RESULTS

Fetuses of 970 participants had biometry scans. The median number of scans per gestational week was 48 (interquartile range, 43-53). Z-score comparison indicated that the WHO 10^th , 50^th and 90^th centiles of the EFW reference were consistently higher than the corresponding local centiles, whilst the INTERGROWTH-21^st 10^th centile was lower. Fewer than 2% of fetuses scanned at or after 34 weeks would be considered as potentially large-for-gestational age, irrespective of which model was used to predict weight. Adopting the WHO international reference would result in approximately one in six fetuses being regarded as potentially small-for-gestational age, 50% more than the number determined using a population-specific reference. Systematic errors of extrapolated EFW were similar, ranging from 5.5% to 7.4%.

CONCLUSIONS

Centers seeking to use new references, such as the INTERGROWTH-21^st and/or WHO international references, as a means of determining whether a fetus is small- or large-for-gestational age, would be advised to assess the suitability of these references within their own population using standardized methodology. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Three decades of neonatal vaccination has greatly reduced antenatal prevalence of hepatitis B virus infection among gravidae covered by the program

OBJECTIVES

To evaluate the impact of three decades of hepatitis B vaccination in infancy on antenatal prevalence of hepatitis B surface antigen (HBsAg) carriage in 93,134 Hong-Kong born gravidae managed in 1997-2015.

METHODS

Annual prevalence of HBsAg carriage on routine antenatal screening was examined with respect to maternal year of birth in three periods i.e. pre-1983 (before availability of vaccination), 1983-1988 (vaccination of infants born to HBsAg-carriers), and after 1988 (universal vaccination).

RESULTS

Overall HBsAg carriage was 8.3% (7737/93,134), decreasing from 10.5% in 1997 to 6.5% in 2015 (p < 0.001), and from 8.8%, 7.0% to 3.1%, respectively, for the three period-of-birth cohorts (p < 0.001). Annual prevalence decreased from 9.9% in 1997 to 7.5% in 2015 (p < 0.001) in the pre-1983 cohort, but showed neither difference nor trend in the other two cohorts. However, the annual prevalence showed significantly falling trends from the pre-1983 to the post-1988 cohorts for the years 2007-2008 and 2010-2015.

CONCLUSIONS

A progressive decline in overall annual prevalence of antenatal HBsAg carriage was found, with a consistently significant decline among the three cohorts for the years 2007-2008 and 2010-2015, providing evidence that universal hepatitis B vaccination in infancy has reduced significantly antenatal prevalence of HBsAg carriage in Hong Kong.

Heart Failure and Frailty in the Community-Living Elderly Population: What the UFO Study Will Tell Us

Heart failure and frailty are clinical syndromes that present with overlapping phenotypic characteristics. Importantly, their co-presence is associated with increased mortality and morbidity. While mechanical and electrical device therapies for heart failure are vital for select patients with advanced stage disease, the majority of patients and especially those with undiagnosed heart failure would benefit from early disease detection and prompt initiation of guideline-directed medical therapies. In this article, we review the problematic interactions between heart failure and frailty, introduce a focused cardiac screening program for community-living elderly initiated by a mobile communication device app leading to the Undiagnosed heart Failure in frail Older individuals (UFO) study, and discuss how the knowledge of pre-frailty and frailty status could be exploited for the detection of previously undiagnosed heart failure or advanced cardiac disease. The widespread use of mobile devices coupled with increasing availability of novel, effective medical and minimally invasive therapies have incentivized new approaches to heart failure case finding and disease management.

First trimester screening for pre-eclampsia in Chinese pregnancies: case-control study

OBJECTIVE

To assess the potential of screening for pre-eclampsia (PE) in a Chinese population.

DESIGN

Case-control study.

SETTING

Teaching hospital in Hong Kong.

POPULATION

A total of 3330 women having a viable singleton pregnancy attending first-trimester Down-syndrome screening.

METHODS

Mean arterial pressure (MAP), bilateral uterine artery pulsatility index (UtA-PI), and placental growth factor (PlGF) were measured. Screening markers were transformed to multiples of the gestational median (MoM) and adjusted for maternal and pregnancy characteristics. MoM distributions in PE and non-PE pregnancies were compared with published expected values. PE screening performance was assessed using area under receiver operating curves (AUROC).

MAIN OUTCOME MEASURES

PE detection rate.

RESULTS

A total of 30 (0.9%) women developed either early (<34 weeks) or late (≥34 weeks) onset PE. MAP was dependent on maternal BMI, UtA-PI on fetal crown rump length, uterine artery peak systolic velocity (UtA-PSV) on maternal age and gestation, and PlGF on gestation in non-PE pregnancies. MoM distributions determined using published Fetal Medicine Foundation models deviated significantly from one for both MAP (P < 0.0001) and PI (P < 0.0001), but not PlGF (P = 0.52) in non-PE pregnancies, whilst PlGF MoM distributions in those who developed early as opposed to late onset PE were significantly higher (P = <0.05). AUROC for any PE using multiple markers was 0.72 (95% CI: 0.64-0.81) with detection rates of 72 and 55% for early and late PE, respectively, for a 10% false positive rate.

CONCLUSION

Detection rates for PE in our Chinese population were lower than the expected 90-95% even after adjusting MoM for local women's characteristics.

FUNDING

General Research Fund (Project number 470513).

TWEETABLE ABSTRACT

Pre-eclampsia screening in the Chinese population had detection rates lower than previously published results.

Maternal height and risk of hypertensive disorders in pregnancy

PURPOSE

The relationship between maternal height and gestational hypertensive disorders was examined in a cohort of Chinese gravidae managed in 1997-2013 to clarify the association between short stature with preeclampsia (PE) and gestational hypertension (GH).

MATERIALS AND METHODS

Retrospective study of 87 290 gravidae categorized by their height into four quartile groups. The impact of short stature, defined as height in the lowest quartile, on incidence of PE and GH was studied in relation to the presence of risk factors. The independent role of short stature was determined by regression analysis.

RESULTS

The 25th, 50th, and 75th percentile values of height were 154 cm, 158 cm, and 161 cm respectively. The incidence of PE, but not GH, was inversely correlated with height (p = .025). Short stature altered the impact of parity status, advanced age, high body mass index, infant gender, and medical history, on incidence of PE but not GH. On regression analysis, short stature increased risk of PE (adjusted RR 1.134, 95%CI 1.005-1.279) but reduced GH (adjusted RR 0.836, 95%CI 0.718-0.974).

CONCLUSIONS

Maternal short stature should be defined according to distribution in a specific ethnic group, and it exerts a significant but opposite effect on the incidence of PE versus GH.

Impact of the two-dose rubella vaccination regimen on incidence of rubella seronegativity in gravidae aged 25 years and younger

Objective

This study compared the incidence of rubella seronegativity among gravidae of 25 year-old and younger, between those born in Hong Kong after 1983 when the two-dose rubella vaccination was implemented, versus gravidae born before, to examine the impact of the two-dose regimen.

Methods

In this retrospective cohort study, the incidence of antenatal rubella seronegativity in our parturients managed in1997-2015 was analysed by their age from ≤16 to 25 years, and the effect of year of birth was determined adjusting for confounding factors including teenage status, obstetric history, anthropometric factors, and health parameters including anaemia, thalassaemia trait and hepatitis B carrier status.

Results

Among the 12743 gravidae, the 6103 gravidae born after 1983 had overall higher rubella seronegativity (9.1% versus 4.4%, OR 2.061, 95% CI 1.797–2.364), with significant difference (p = 0.006) and inverse correlation (p<0.001) with age, in contrast to the 6640 gravidae born in/before 1983 whom there was significant difference (p = 0.027) but a positive correlation (p = 0.008) with age. For each year of age, the former had significantly higher incidence of rubella seronegativity except for those of ≤16 years. Regression analysis confirmed that birth after 1983 was independently associated with rubella seronegativity (aOR 2.207, 95% CI 1.902–2.562).

Conclusion

There was a significant trend between rubella seronegativity with age in young gravidae, but the pattern was opposite between gravidae born after versus in/before 1983, with the former having a higher incidence of seronegativity at all ages. Young women covered by the two-dose rubella immunisation programme have a paradoxically higher incidence of rubella seronegativity.

Prior pregnancy and antenatal rubella sero-negativity-evidence of persistent maternal immunologic alteration?

PROBLEM

It is unclear if the immunologic alterations induced by pregnancy could persist.

METHOD OF STUDY

Antenatal rubella sero-negativity was correlated with gravidity, abortions and parity in 112 083 gravidae managed during 1997-2015, with further analysis stratified for factors known to influence rubella serology.

RESULTS

The 10.2% sero-negative gravidae had different characteristics, and the incidence showed significant difference and positive trend (P<.001 for both) with gravidity, abortions and parity. The pattern remained consistent when analysis was stratified for advanced age, high body mass index and medical history, but was negated by hepatitis B virus infection except for abortions, and by high body mass index for parity. For gravidity 2-4, no difference in rubella sero-negativity was found between gravidae with all previous pregnancies ended in abortion vs delivery.

CONCLUSION

Prior pregnancies diminished rubella immunity in a dose-dependent manner, which may be a reflection of the cumulative effect of pregnancy-associated maternal immunologic alteration.

Triplet pregnancy with fetal reduction: experience in Hong Kong

INTRODUCTION

Triplet and higher-order multiple pregnancies are well known to be associated with increased adverse outcomes. This study reviewed the perinatal outcomes in women with a triplet pregnancy who underwent fetal reduction versus expectant management at a university hospital in Hong Kong.

METHODS

This was a retrospective review of triplet pregnancies at Prince of Wales Hospital in Hong Kong from 1 January 2008 to 30 September 2014. Women carrying a triplet pregnancy were classified as having had expectant management, fetal reduction to twins, or fetal reduction to a singleton. Maternal and pregnancy characteristics were compared. Outcome measures included fetal loss, gestational age at delivery, birth weight, neonatal survival rate, neonatal death, neonatal complications, and need for and length of neonatal intensive care unit stay.

RESULTS

A total of 52 triplet pregnancies were identified. One pregnancy that was lost to follow-up and one that was terminated were excluded. The majority of pregnancies (84%) were the result of assisted reproductive technology. Fetal reduction was performed in 26 (52%) pregnancies, of which 22 were reduced to twins and four to a singleton. The mean gestations at delivery were 32.6, 35.2, and 39.6 weeks in the expectant management, fetal reduction to twins, and fetal reduction to a singleton groups, respectively. Significantly more pregnancies with expectant management resulted in a preterm birth. All pregnancies with fetal reduction to a singleton resulted in a term birth. A higher mean birth weight, lower neonatal death rate, and reduced need for admission to and length of stay in the neonatal intensive care unit were observed in the fetal reduction groups.

CONCLUSIONS

Approximately 50% of women with a triplet pregnancy in Hong Kong elected to undergo fetal reduction. This was associated with a significant reduction in extreme preterm delivery and associated morbidity and mortality.

Pregnancy and maternal chronic hepatitis B infection-Evidence of reproductive advantage?

PROBLEM

As multiparas have high prevalence of chronic hepatitis B virus (HBV) infection, we examined here the relationship between the number of pregnancies with HBV infection.

METHOD OF STUDY

Retrospective cohort study examining the prevalence of HBV infection by actual gravidity and parity in 104 242 gravidae managed during 1997-2013.

RESULTS

Infection rate increased from 8.5% to 10.6% for G1 to G≥6 and from 8.8% to 10.0% for P0 to P≥3 (P<.001). When stratified by parity, correlation with gravidity was maintained in the nulliparous gravidae. For the same gravidity, increasing parity was associated with higher rate of HBV infection for G2 and G3. Multiparas had higher HBV infection prevalence (all >10%) than nulliparas (<10%) for G2 to G≥4.

CONCLUSION

Prior pregnancies, especially successful ones, are associated with increased HBV infection in an endemic population, which could have enhanced reproduction and in the process facilitated its transmission to the following generations.

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.

Reappraisal of endometrial thickness for the detection of endometrial cancer in postmenopausal bleeding: a retrospective cohort study

OBJECTIVE

To estimate the accuracy of transvaginal ultrasound (TVS) measurement of endometrial thickness (ET) in diagnosing endometrial cancer in postmenopausal women with vaginal bleeding (PMB).

DESIGN

Retrospective cohort study.

SETTING

One-stop PMB clinic in a Hong Kong teaching hospital.

POPULATION

A cohort of 4383 women with PMB.

METHODS

Transvaginal ultrasonic measurement of ET and endometrial biopsies were obtained in women presenting with PMB between 2002 and 2013. Endometrial histology was used as the reference standard to calculate accuracy estimates.

MAIN OUTCOME MEASURES

Accuracy data for TVS ET presented as sensitivity, specificity, and area under the receiver operator characteristic (ROC) curve.

RESULTS

Endometrial cancer was diagnosed in 3.8% of women. The median ET in those with endometrial cancer was significantly higher than those with benign conditions (15.7 versus 3.2 mm, P < 0.001). The area under the ROC curve was 0.92 (95% CI 0.89-0.94). The sensitivity for the detection of endometrial cancer at 3-, 4-, and 5-mm cut-offs were 97.0% (95% CI 94.5-99.6%), 94.1% (95% CI 90.5-97.6%), and 93.5% (95% CI 89.7-97.2%), respectively. The corresponding estimates of specificity at these thresholds were 45.3% (95% CI 43.8-46.8%), 66.8% (65.4-68.2%), and 74.0% (72.7-75.4%).

CONCLUSIONS

Transvaginal ultrasound using a 3-mm cut-off has high sensitivity for detecting endometrial cancer and can identify women with PMB who are highly unlikely to have endometrial cancer, thereby avoiding more invasive endometrial biopsy.

Maternal ABO and rhesus blood group phenotypes and hepatitis B surface antigen carriage

In view of a persistently high prevalence of hepatitis B surface antigen (HBsAg) carriage in our obstetric population, we examined the association between HBsAg carriage with maternal ABO and rhesus (Rh) blood group phenotypes determined at routine antenatal screening. In a retrospective study, the antenatal screening results of women booked for confinement between 1998 and 2011 in our hospital were examined for the relationship between HBsAg carriage with the ABO and rhesus blood groups, taking into account also the effects of advanced maternal age (≥ 35 years) and parity status (nulliparous or multiparous), and year of birth before or following the availability of the hepatitis B vaccine (1984). HBsAg carriage was found in 9.9%, 9.6%, 9.1% and 10.2% (P = 0.037) for group-A (n = 20 581 or 26.1%), -B (n = 20 744 or 26.4%), -AB (n = 5138 or 6.5%) and -O (n = 32 242 or 41.0%) among the 78705 women in the study cohort. Rhesus negativity was found in 0.6%, and HBsAg carriage was 12.3% and 9.8%, respectively, for the Rh-negative and Rh-positive women (P = 0.071). Carriage rate between group-O and non-O was influenced by nulliparity, age ≥ 35 years and Rh-positive status. Regression analysis indicated that group-B (P = 0.044, aOR = 1.062, 95% CI 1.002-1.127) and group-AB (P = 0.016, aOR = 1.134, 95% CI 1.024-1.256) were associated with HBsAg carriage. Blood groups-B and -AB are associated with increased hepatitis B virus (HBV) infection in our population, and further studies are warranted to elucidate the implications of this on the sequelae of HBV infection.

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.