The duration of pregnancy is influenced by fetal and maternal genetic and non-genetic factors. Here we report a fetal genome-wide association meta-analysis of gestational duration, and early preterm, preterm, and postterm birth in 84,689 infants. One locus on chromosome 2q13 is associated with gestational duration; the association is replicated in 9,291 additional infants (combined P = 3.96 × 10 −14 ). Analysis of 15,588 mother-child pairs shows that the association is driven by fetal rather than maternal genotype. Functional experiments show that the lead SNP, rs7594852, alters the binding of the HIC1 transcriptional repressor. Genes at the locus include several interleukin 1 family members with roles in pro-inflammatory pathways that are central to the process of parturition. Further understanding of the underlying mechanisms will be of great public health importance, since giving birth either before or after the window of term gestation is associated with increased morbidity and mortality.

OBJECTIVE: To develop and validate a predictive risk calculator for cesarean delivery among women undergoing induction of labor. METHODS: We performed a population-based cohort study of all women who had singleton live births after undergoing induction of labor from 32 0/7 to 42 6/7 weeks of gestation in the United States from 2012 to 2016. The primary objective was to build a predictive model estimating the probability of cesarean delivery after induction of labor using antenatal factors obtained from de-identified U.S. live-birth records. Multivariable logistic regression estimated the association of these factors on risk of cesarean delivery. K-fold cross validation was performed for internal validation of the model, followed by external validation using a separate live-birth cohort from 2017. A publicly available online calculator was developed after validation and calibration were performed for individual risk assessment. The seven variables selected for inclusion in the model by magnitude of influence were prior vaginal delivery, maternal weight at delivery, maternal height, maternal age, prior cesarean delivery, gestational age at induction, and maternal race. RESULTS: From 2012 to 2016, there were 19,844,580 live births in the United States, of which 4,177,644 women with singleton gestations underwent induction of labor. Among these women, 800,423 (19.2%) delivered by cesarean. The receiver operating characteristic curve for the seven-variable model achieved an area under the curve (AUC) of 0.787 (95% CI 0.786–0.788). External validation demonstrated a consistent measure of discrimination with an AUC of 0.783 (95% CI 0.764–0.802). CONCLUSION: This validated predictive model uses seven variables that were obtainable from the patient's medical record and discriminates between women at increased or decreased risk of cesarean delivery after induction of labor. This risk calculator, found at https://ob.tools/iol-calc, can be used in addition to the Bishop score by health care providers in counseling women who are undergoing an induction of labor and allocating appropriate resources for women at high risk for cesarean delivery.

OBJECTIVE: To quantify the reported prevalence and trend of maternal hepatitis C virus (HCV) infection in the United States (2009–2017) and identify maternal characteristics and obstetric outcomes associated with HCV infection during pregnancy. METHODS: We conducted a population-based retrospective cohort study of all live births in the United States for the period 2009 through 2017 using National Center for Health Statistics birth records. We estimated reported prevalence and trends over this time period for the United States. We also evaluated demographic factors and pregnancy outcomes associated with maternal HCV infection for a contemporary U.S. cohort (2014–2017). RESULTS: During the 9-year study period, there were 94,824 reported cases of maternal HCV infection among 31,207,898 (0.30%) live births in the United States. The rate of maternal HCV infection increased from 1.8 cases per 1,000 live births to 4.7 cases per 1,000 live births (relative risk [RR] 2.7, 95% CI 2.6–2.8) in the United States. After adjusting for various confounders in the contemporary U.S. cohort (2014–2017), demographic characteristics associated with HCV infection included non-Hispanic white race (adjusted RR 2.8, 95% CI 2.7–2.8), Medicaid insurance (adjusted RR 3.3, CI 3.2–3.3), and cigarette smoking (adjusted RR 11.1, CI 10.9–11.3). Co-infection during pregnancy with hepatitis B (adjusted RR 19.2, CI 18.1–20.3), gonorrhea, chlamydia, or syphilis were also associated with maternal HCV infection. Obstetric and neonatal outcomes associated with maternal HCV infection included cesarean delivery, preterm birth, maternal intensive care unit admission, blood transfusion, having small-for-gestational-age neonates (less than the 10th percentile) birth weight, neonatal intensive care unit admission, need for assisted neonatal ventilation, and neonatal death. CONCLUSION: The reported prevalence of maternal HCV infection has increased 161% from 2009 to 2017.