Stillbirth: tissue findings with environmental and genetic links

Do maternal BMI and gestational weight gain equally affect the risk of infant hypoxic and traumatic events?

BACKGROUND

Small (SGA) and large (LGA) for gestational age infants have higher risks of infant morbidity when compared to those who are appropriate for gestational age (AGA). Increasing pre-pregnancy maternal BMI and gestational weight gain (GWG) are associated with higher risks of LGA and lower risks of SGA infants; however, their direct effects on infant morbidity are unknown. Therefore, we intended to 1) assess how maternal pre-pregnancy BMI, GWG, and birthweight (categorized as SGA, AGA or LGA) affect infant morbidity and 2) estimate at entry of care the risk of infant morbidity according to pre-pregnancy BMI and possible GWG.

METHODS

we used Consortium on Safe Labor data, a retrospective observational cohort study collecting pregnancy and birth data from 2002 to 2008 in 12 US centers. The association between maternal BMI, GWG and infant morbidity was estimated in singleton gestations delivering ≥ 37 weeks using binomial logistic regression. Hypoxic composite neonatal morbidity was defined as any the following: stillbirth, neonatal death, resuscitation at birth, NICU admission, intracranial hemorrhage, PVH grade III and IV, neonatal seizures, NEC, meconium aspiration, CPAP or mechanical ventilation, RDS, and sepsis. Traumatic composite neonatal morbidity included shoulder dystocia or birth injuries.

RESULTS

In this study of 110,594 mother-infant dyads, a total of 8,369 (7.6%) infants experienced hypoxic, while 2,134 (1.9%) developed traumatic morbidity. The risk of hypoxic morbidity among SGA, AGA and LGA infants increased when mothers were overweight (aOR 1.26 [95%CI 1.18-1.34]) or obese (class 1: aOR 1.3 [1.2-1.4]; class 2: aOR 1.7 [1.5-1.9]; class 3: aOR 1.8 [1.6-2]) as opposed to normal weight, and when GWG exceeded (aOR 1.08 [1.02-1.014]) rather than remained within recommendations. The risk of traumatic morbidity increased with maternal obesity (class 1: aOR 1.3 [1.1-1.5]), whilst it dropped with GWG below recommendations (aOR 0.7 [0.6-0.8]). The risk of hypoxic events estimated at entry of care increased with maternal overweight (aOR 1.27 [1.19-1.35]) or obesity (class 1: aOR 1.4 [1.2-1.5]; class 2: aOR 1.7 [1.5-1.9]; class 3: aOR 1.8 [1.6-2.1]), and with possible GWG above (aOR 1.09 [1.03-1.015]) recommendations. The risk of traumatic morbidity increased with overweight (aOR 1.1 [1-1.3]) or obesity (class 1: aOR 1.4 [1.2-1.6]; class 2: aOR 1.3 [1-1.6]), with possible GWG above (aOR 1.2 [1-1.3]), as opposed to below recommendations (aOR 0.7 [0.6-0.8]).

CONCLUSIONS

While maternal pre-pregnancy BMI and GWG equally affected traumatic morbidity, the former had a greater impact on hypoxic complications. Therefore, weight control prior to pregnancy is at least as effective as avoiding excessive gestational weight gain to prevent neonatal morbidity.

Obesity as a potential risk factor for stillbirth: The Japan Environment and Children's Study

The relationship between high body mass index (BMI) >25 kg/m2 and risk for stillbirth in the Japanese population remains unclear. This study aimed to estimate the impact of maternal obesity on the risk of stillbirth in a Japanese population. This prospective cohort study used data from the Japan Environment and Children's Study, which recruited pregnant individuals between 2011 and 2014. A total of 93,772 fetuses were considered eligible for inclusion in this study. Stillbirth (fetal death before or during labor at ≥22 completed weeks of gestation) rates were compared among four pre-pregnancy BMI groups: underweight (<18.5 kg/m2), reference (18.5 to <25.0 kg/m2), overweight (25.0 to <30.0 kg/m2), and obese (≥30.0 kg/m2). The association between pre-pregnancy BMI and the risk of stillbirth was estimated using multiple logistic regression analyses. The overall stillbirth incidence was 0.33% (305/93,722). Compared with the reference group, the risk of stillbirth was significantly higher in the overweight group (adjusted odds ratio [aOR]: 1.55; 95% confidence interval [CI]: 1.08-2.23) and the obese group (aOR: 2.60; 95% CI: 1.59-4.24). The overall incidence of early stillbirth (i.e., <28 weeks) was 0.17% (155/93,722). Similarly, after adjusting for potential confounding factors, the risk of early stillbirth was significantly higher in the obese group (aOR: 4.33; 95% CI: 2.44-7.70). Increased maternal BMI was associated with an increased risk of stillbirth in the Japanese population. Therefore, counselling women planning for pregnancy on the importance of an appropriate pre-pregnancy BMI to minimize the risk of stillbirth is important.

Association of Maternal Body Mass Index With Risk of Infant Mortality: A Dose-Response Meta-Analysis

Objective: This study presumed that a high or low body mass index (BMI) might increase the risk of infant mortality. Therefore, a meta-analysis was performed to systematically assess the association between maternal BMI and the risk of infant mortality. Methods: The electronic databases, including Pubmed, Embase database, and Cochrane Library, were systemically searched by two investigators from inception to November 26th, 2020, with no language restriction. In parallel, a dose-response was assessed. Results: Finally, 22 cohort studies involving 13,532,293 participants were included into this paper, which showed that compared with normal BMI, maternal overweight significantly increased the risks of infant mortality [risk ratio (RR), 1.16; 95% confidence interval (CI), 1.13-1.19], neonatal mortality (RR, 1.23; 95% CI, 1.08-1.39), early neonatal mortality (RR, 1.55; 95% CI, 1.26-1.92) and post-neonatal mortality (RR, 1.18; 95% CI, 1.07-1.29). Similarly, maternal obesity significantly increased the risk of infant mortality (RR, 1.55; 95% CI, 1.41-1.70), neonatal mortality (RR, 1.55; 95% CI, 1.28-1.67), early neonatal mortality (RR, 1.37; 95% CI, 1.13-1.67), and post-neonatal mortality (RR, 1.30; 95% CI, 1.03-1.65), whereas maternal underweight potentially decreased the risk of infant mortality (RR, 0.93; 95% CI, 0.88-0.98). In the dose-response analysis, the risk of infant mortality significantly increased when the maternal BMI was >25 kg/m². Conclusions: Maternal overweight or obesity significantly increases the risks of infant mortality, neonatal mortality, early neonatal mortality, and post-neonatal mortality compared with normal BMI in a dose-dependent manner. Besides, maternal underweight will not increase the risk of infant mortality, neonatal mortality, early neonatal mortality, or postneonatal mortality; instead, it tends to decrease the risk of infant mortality. Early weight management may provide potential benefits to infants, and more large-scale prospective studies are needed to verify this finding in the future.

Symptomatic dengue infection during pregnancy and the risk of stillbirth in Brazil, 2006-12: a matched case-control study

BACKGROUND

Maternal infections during pregnancy can increase the risk of fetal death. Dengue infection is common, but little is known about its role in fetal mortality. We aimed to investigate the association between symptomatic dengue infection during pregnancy and fetal death.

METHODS

We did a nested case-control study using obstetrician-collected data from the Brazilian livebirth information system (SINASC), the mortality information system (SIM), and the national reportable disease information system (SINAN). We identified all pregnancies ending in stillbirth and a random sample of livebirths between Jan 1, 2006, and Dec 31, 2012. We did linkage to determine which mothers were diagnosed with dengue infection during pregnancy. By use of stillbirths as cases and a sample of matched livebirths as a control, we calculated matched odds ratios (mORs) using conditional logistic regression adjusted for maternal age and education.

FINDINGS

275 (0·2%) of 162 188 women who had stillbirths and 1507 (0·1%) of 1 586 105 women who had livebirths were diagnosed with dengue infection during pregnancy. Symptomatic dengue infection during pregnancy almost doubled the odds of fetal death (mOR 1·9, 95% CI 1·6-2·2). The increase in risk was similar when analyses were restricted to laboratory-confirmed cases of dengue infection (1·8, 1·4-2·4). Severe dengue infection increased the risk of fetal death by about five times (4·9, 2·3-10·2).

INTERPRETATION

Symptomatic dengue infection during pregnancy is associated with an increased risk of fetal death. We recommend further epidemiological and biological studies of the association between dengue and poor birth outcomes to measure the burden of subclinical infections and elucidate pathological mechanisms.

FUNDING

Brazilian National Council for Scientific and Technological Development, Horizon 2020.

Periconceptional intake of vitamins and fetal death: a cohort study on multivitamins and folate

BACKGROUND

Women planning to conceive are often advised to take multivitamins. Whether this affects the survival of the fetus is not known.

METHODS

We used data from 35 914 women in the Danish National Birth Cohort who at recruitment had reported the number of weeks of supplement use during a 12-week periconceptional period. A telephone interview provided information about maternal characteristics and data on fetal death came from registers. The associations between periconceptional multivitamin or folate-only use and early (<20 weeks) and late (≥20 weeks) fetal death were estimated by hazard ratios (HR) with 95% confidence intervals (CI). Follow-up started at 8 completed weeks of gestation, and comparisons were made with no supplement use at any time during the periconceptional period.

RESULTS

Any multivitamin use was associated with a small increased crude risk of fetal death [HR 1.12 (1.01-1.25)], which was restricted to early losses [HR 1.18 (1.05-1.33)] compared with late losses [HR 0.82 (0.62-1.10)]. Adjustment for maternal factors increased this excess risk further. Whereas regular users of multivitamins (4-6 weeks of 6) before conception had more early losses [HR 1.29 (1.12-1.48)], a decreased risk of late losses was indicated when use started after conception [HR 0.65 (0.39-1.09)]. Folate-only use was not associated with fetal death.

CONCLUSIONS

Multivitamin use was associated with a modest increased risk of early fetal death. For late fetal death, regular supplement use after conception may decrease risk, but numbers were small. Further studies on preconceptional multivitamin use are needed to guide public health recommendations.

Twin pregnancies with single fetal death: analysis of 38 cases

The objective of this study is to evaluate fetal and maternal outcomes of twin pregnancies with intrauterine single fetal death. In 13 cases, intrauterine death of one fetus was found during the first trimester; in 25 cases, it was found after the first trimester. Obstetric complications and fibrinogen levels were compared. There were no significant differences in the number of preterm delivery, preeclampsia, and intrauterine growth restriction and there were significant differences in gestational age at delivery and birth weight between groups. Coagulation disorders did not occur. The risk for adverse pregnancy outcomes with a single fetal death during and after the first trimester is similar.

Association between fetal interleukin-1 receptor antagonist gene polymorphism and unexplained fetal death

OBJECTIVE

In spite of extensive clinical examinations or autopsies, as many as 15% to 40% of stillbirths remain unexplained. A systemic fetal inflammatory response is an independent risk factor for severe neonatal morbidity, mediated by proinflammatory cytokines. As a major anti-inflammatory cytokine, interleukin-1 receptor antagonist (IL-1ra) plays a crucial role modulating the proinflammatory response. The gene coding for IL-1ra (IL1RN) is polymorphic. We hypothesized that fetal possession of a specific allele, IL-1RN*2, associated with increased proinflammatory responses, may increase susceptibility to intrauterine fetal death.

STUDY DESIGN

Fetal kidney cells were obtained from paraffin blocks of 27 unexplained stillbirths. DNA was isolated and tested for IL-1RN genotypes by polymerase chain reaction. As a control group, DNA from 302 live births was also tested.

RESULTS

There was an enhanced rate of IL-1RN*2 homozygocity, 41%, among unexplained stillbirths compared with the control group, 8.6% (P < .001). Histologic analysis of fetal tissues demonstrated a predominant proinflammatory response in IL-1RN*2 homozygote fetuses. Extensive screening (microbiology, maternal serology, placenta histology) did not identify any specific trigger agent.

CONCLUSION

There is an association between unexplained stillbirth and fetal homozygous IL1RN*2 carriage.

Prepregnancy obesity and fetal death: a study within the Danish National Birth Cohort

OBJECTIVE

To examine the association between high prepregnancy body mass index and fetal death, allowing for the effects of gestational age, weight gain, and maternal diseases in pregnancy.

METHODS

Prepregnancy body mass index (BMI) and fetal death were examined in the Danish National Birth Cohort among 54,505 pregnant women who participated in a comprehensive interview during the second trimester. Pregnancy outcomes were obtained from registers and medical records. Cox regression analyses with delayed entry and time-dependent covariates were used to estimate the risk of fetal death.

RESULTS

Compared with normal-weight women (18.5 < or = BMI < 25), the risks of fetal death among obese women (BMI > or = 30), expressed as adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were as follows: before week 14: 0.8 (0.5-1.4), weeks 14-19: 1.6 (1.0-2.5), weeks 20-27: 1.9 (1.1-3.3), weeks 28-36: 2.1 (1.0-4.4), weeks 37-39: 3.5 (1.9-6.4), and weeks 40+: 4.6 (1.6-13.4). Overweight women (25 < or = BMI < 30) also experienced a higher risk after 28 weeks, and especially after 40 weeks of gestation (HR 2.9, 95% CI 1.1-7.7). Analysis of stillbirth (fetal death at 28+ completed weeks of gestation) indicated that the effects were not due to obesity-related diseases in pregnancy, nor was weight gain associated with stillbirth. The increased risk of stillbirth among overweight and obese women was partly attributable to inadequate placental function (crude odds ratios 2.1, 95% CI 1.0-4.4, and 5.2, 95% CI 2.5-10.9, respectively).

CONCLUSION

Prepregnancy obesity was associated with an increasing excess risk of fetal death with advancing gestation, and placental dysfunction may be a possible contributing factor.

Management of single fetal demise in a multiple gestation

Intrauterine fetal demise of 1 twin in a multiple gestation is a complex clinical situation. Chorionicity, gestational age at diagnosis, problems specific to the pregnancy, and the emotional needs of the patient can impact management. Strategies to optimize outcomes may include a multidisciplinary team approach and fetal surveillance. The following article reviews (1) adverse fetal and neonatal outcomes associated with intrauterine fetal demise of 1 twin, (2) the potential maternal impact, and (3) the strategies to possibly prevent poor outcomes. It is important to remember that even the most vigilant care may not avoid adverse sequelae in a portion of at-risk pregnancies.