Cesarean Section and Subsequent Stillbirth, Is Confounding by Indication Responsible for the Apparent Association? An Updated Cohort Analysis of a Large Perinatal Database

Delivery of a Fetus with a Non-Reassuring Status Is Associated with Significant Maternal Morbidity

OBJECTIVES

When a labor process is complicated by non-reassuring fetal status (NRFS), obstetricians focus on delivery to optimize neonatal status. We explored maternal morbidity in the setting of NRFS. Our hypothesis is that delivery of a live newborn with NRFS is associated with significant maternal morbidity. Design, Participants, Setting, and Methods: A large retrospective cohort study of 27,886 women who delivered between January 2013 and December 2016 in a single health system was studied. Inclusion criteria included (1) women over the age of 18 at the time of admission; (2) singleton pregnancy; (3) live birth; and (4) gestational age greater than or equal to 37 weeks at the time of admission. NRFS was defined as umbilical cord pH less than or equal to 7.00, fetal bradycardia, late decelerations, and/or umbilical artery base excess ≤-12. Univariate and multivariate logistic regression and propensity score analyses were performed, and propensity score adjusted odds ratios (AORPS) were derived. p values <0.05 were considered statistically significant. Primary outcomes are maternal blood transfusion, maternal readmission, maternal intensive care unit (ICU) admission, and cesarean delivery in relation to umbilical artery pH, fetal bradycardia, and late decelerations.

RESULTS

Umbilical artery pH less than or equal to 7 was associated with maternal blood transfusion (AORPS 6.83 [95% CI 2.22-21.0, p < 0.001]), maternal readmission (AORPS 12.6 [95% CI 2.26-69.8, p = 0.0039]), and cesarean delivery (AORPS 5.76 [95% CI 3.63-9.15, p < 0.0001]). Fetal bradycardia was associated with transfusion (AORPS 2.13 [95% CI 1.26-3.59, p < 0.005]) and maternal ICU admission (AORPS 3.22 [95% CI 1.23-8.46, p < 0.017]). Late decelerations were associated with cesarean delivery (AORPS 1.65 [95% CI 1.55-1.76, p < 0.0001]), clinical chorioamnionitis (AORPS 2.88 [95% CI 2.46-3.37, p < 0.0001]), and maternal need for antibiotics (AORPS 1.89 [95% CI 1.66-2.15, p < 0.0001]). Umbilical artery base excess less than or equal to -12 was associated with readmission (AORPS 6.71 [95% CI 2.22-20.3, p = 0.0007]), clinical chorioamnionitis (AORPS 1.89 [95% CI 1.24-2.89, p = 0.0031]), and maternal need for antibiotics (AORPS 1.53 [95% CI 1.03-2.26, p = 0.0344]).

LIMITATIONS

The retrospective design contributes to potential bias compared to the prospective design. However, by utilizing multivariate logistic regression analysis with a propensity score method, specifically inverse probability of treatment weighting, we attempted to minimize the impact of confounding variables. Additionally, only a portion of the data set had quantitative blood losses recorded, while the remainder had estimated blood losses.

CONCLUSION

NRFS is associated with significant maternal complications, in the form of increased need for blood transfusions, ICU admissions, and increased infection and readmission rates. Strategies for minimizing maternal complications need to be proactively considered in the management of NRFS.

Management of Stillbirth: Obstetric Care Consensus No, 10

Stillbirth is one of the most common adverse pregnancy outcomes, occurring in 1 in 160 deliveries in the United States. In developed countries, the most prevalent risk factors associated with stillbirth are non-Hispanic black race, nulliparity, advanced maternal age, obesity, preexisting diabetes, chronic hypertension, smoking, alcohol use, having a pregnancy using assisted reproductive technology, multiple gestation, male fetal sex, unmarried status, and past obstetric history. Although some of these factors may be modifiable (such as smoking), many are not. The study of specific causes of stillbirth has been hampered by the lack of uniform protocols to evaluate and classify stillbirths and by decreasing autopsy rates. In any specific case, it may be difficult to assign a definite cause to a stillbirth. A significant proportion of stillbirths remains unexplained even after a thorough evaluation. Evaluation of a stillbirth should include fetal autopsy; gross and histologic examination of the placenta, umbilical cord, and membranes; and genetic evaluation. The method and timing of delivery after a stillbirth depend on the gestational age at which the death occurred, maternal obstetric history (eg, previous hysterotomy), and maternal preference. Health care providers should weigh the risks and benefits of each strategy in a given clinical scenario and consider available institutional expertise. Patient support should include emotional support and clear communication of test results. Referral to a bereavement counselor, peer support group, or mental health professional may be advisable for management of grief and depression.

Obstetric Care Consensus #10: Management of Stillbirth: (Replaces Practice Bulletin Number 102, March 2009)

Stillbirth is one of the most common adverse pregnancy outcomes, occurring in 1 in 160 deliveries in the United States. In developed countries, the most prevalent risk factors associated with stillbirth are non-Hispanic black race, nulliparity, advanced maternal age, obesity, preexisting diabetes, chronic hypertension, smoking, alcohol use, having a pregnancy using assisted reproductive technology, multiple gestation, male fetal sex, unmarried status, and past obstetric history. Although some of these factors may be modifiable (such as smoking), many are not. The study of specific causes of stillbirth has been hampered by the lack of uniform protocols to evaluate and classify stillbirths and by decreasing autopsy rates. In any specific case, it may be difficult to assign a definite cause to a stillbirth. A significant proportion of stillbirths remains unexplained, even after a thorough evaluation. Evaluation of a stillbirth should include fetal autopsy; gross and histologic examination of the placenta, umbilical cord, and membranes; and genetic evaluation. The method and timing of delivery after a stillbirth depend on the gestational age at which the death occurred, maternal obstetric history (eg, previous hysterotomy), and maternal preference. Health care providers should weigh the risks and benefits of each strategy in a given clinical scenario and consider available institutional expertise. Patient support should include emotional support and clear communication of test results. Referral to a bereavement counselor, peer support group, or mental health professional may be advisable for management of grief and depression.

Risk of preterm birth after prior term cesarean

Objective

To determine the risk of overall preterm birth (PTB) and spontaneous PTB in a pregnancy after a caesarean section (CS) at term.

Design

Longitudinal linked national cohort study.

Setting

The Dutch Perinatal Registry (1999–2009).

Population

268 495 women with two subsequent singleton pregnancies were identified.

Methods

A cohort study based on linked registered data from two subsequent pregnancies in the Netherlands.

Main outcome measures

The incidence of overall PTB and spontaneous PTB with subgroup analysis on gestational age at first delivery and type of CS (planned or unplanned).

Results

Of 268 495 women with a singleton first pregnancy who delivered at term, 15.76% (n = 42 328) had a CS. The incidence of PTB in the second pregnancy was 2.79% (n = 1182) in women with a previous CS versus 2.46% (n = 5570) in women with a previous vaginal delivery (adjusted odds ratio [aOR] 1.14, 95% confidence interval [CI] 1.07–1.21). This increased risk is mainly driven by an increased risk of spontaneous PTB after previous CS at term (aOR 1.50, 95% CI 1.38–1.70). Analysis for type of CS compared with vaginal delivery showed an aOR on spontaneous PTB of 1.86 (95% CI 1.58–2.18) for planned CS and an aOR of 1.40 (95% CI 1.24–1.58) for unplanned CS.

Conclusions

CS at term is associated with a marginally increased risk of spontaneous PTB in a subsequent pregnancy.

Tweetable abstract

Caesarean section at term is associated with a marginally increased risk of spontaneous PTB in a subsequent pregnancy.

Caesarean section at term is associated with a marginally increased risk of spontaneous PTB in a subsequent pregnancy.

Risk of stillbirth among Zambian women with a prior cesarean delivery

OBJECTIVE

Cesarean delivery (CD) may be associated with stillbirth in future pregnancies. We investigated prior CD as a risk factor for stillbirth in Lusaka, Zambia.

METHODS

We conducted a retrospective cohort analysis of women with only one prior pregnancy who delivered between February 1, 2006, and May 31, 2013. We analysed data from the Zambia Electronic Perinatal System. Maternal and infant characteristics were analyzed for association with stillbirth using Pearson's χ² test or the Wilcoxon rank-sum test. We calculated risk ratios for the relationship between stillbirth (antepartum vs intrapartum) and prior CD, with a log Poisson model to adjust for confounding.

RESULTS

Of 57 320 women in our cohort, 1933 (3.4%) reported a prior CD. There were 1012 (1.8%) stillbirths in the no prior CD group and 81 (4.2%) in the prior CD group (P<0.001). In multivariate models adjusting for stillbirth risk factors, prior CD was associated with antepartum (adjusted risk ratio 1.56, 95% confidence interval 1.08-2.24) and intrapartum (adjusted risk ratio 3.26, 95% confidence interval 2.40-4.42) stillbirth compared with no prior CD. The difference between groups was most apparent at 36-37 weeks' gestation (log-rank P<0.001).

CONCLUSION

Prior CD was associated with increased risk of stillbirth. Improved monitoring during labor and safe methods for induction are urgently needed in low-resource settings.

SLC9B1 methylation predicts fetal intolerance of labor

Fetal intolerance of labor is a common indication for delivery by Caesarean section. Diagnosis is based on the presence of category III fetal heart rate tracing, which is an abnormal heart tracing associated with increased likelihood of fetal hypoxia and metabolic acidemia. This study analyzed data from 177 unique women who, during their prenatal visits (7-15 weeks and/or 24-32 weeks) to Atlanta area prenatal care clinics, consented to provide blood samples for DNA methylation (HumanMethylation450 BeadChip) and gene expression (Human HT-12 v4 Expression BeadChip) analyses. We focused on 57 women aged 18-36 (mean 25.4), who had DNA methylation data available from their second prenatal visit. DNA methylation patterns at CpG sites across the genome were interrogated for associations with fetal intolerance of labor. Four CpG sites (P value <8.9 × 10^-9, FDR <0.05) in gene SLC9B1, a Na⁺/H⁺ exchanger, were associated with fetal intolerance of labor. DNA methylation and gene expression were negatively associated when examined longitudinally during pregnancy using a linear mixed-effects model. Positive predictive values of methylation of these four sites ranged from 0.80 to 0.89, while negative predictive values ranged from 0.91 to 0.92. The four CpG sites were also associated with fetal intolerance of labor in an independent cohort (the Johns Hopkins Prospective PPD cohort). Therefore, fetal intolerance of labor could be accurately predicted from maternal blood samples obtained between 24-32 weeks gestation. Fetal intolerance of labor may be accurately predicted from maternal blood samples obtained between 24-32 weeks gestation by assessing DNA methylation patterns of SLC9B1. The identification of pregnant women at elevated risk for fetal intolerance of labor may allow for the development of targeted treatments or management plans.