Perinatal outcomes in grand multiparous women stratified by parity- A large multicenter study

Objective: To assess the effect of each additional delivery among grand multiparous (GMP) women on maternal and neonatal outcomes. Methods: A multi-center retrospective cohort study that examined maternal and neonatal outcomes of GMP women (parity 5-10, analyzed separately for each parity level) compared to a reference group of multiparous women (parity 2-4). The study population included grand multiparous women with singleton gestation who delivered in one of four university-affiliated obstetrical centers in a single geographic area, between 2003 and 2021. We excluded nulliparous, those with parity > 10 (due to small sample sizes), women with previous cesarean deliveries (CDs), multifetal gestations, and out-of-hospital deliveries. The primary outcome of this study was postpartum hemorrhage (PPH, estimated blood loss exceeding 1000 ml, and/or requiring blood product transfusion, and/or a hemoglobin drop > 3 g/Dl). Secondary outcomes included unplanned cesarean deliveries, preterm delivery, along with other adverse maternal and neonatal outcomes. Univariate analysis was followed by multivariable logistic regression. Results: During the study period, 251,786 deliveries of 120,793 patients met the inclusion and exclusion criteria. Of those, 173,113 (69%) were of parity 2-4 (reference group), 27,894 (11%) were of parity five, 19,146 (8%) were of parity six, 13,115 (5%) were of parity seven, 8903 (4%) were of parity eight, 5802 (2%) were of parity nine and 3813 (2%) were of parity ten. GMP women exhibited significantly higher rates of PPH starting from parity eight. The adjusted odds ratios (aOR) were 1.19 (95 % CI: 1.06-1.34) for parity 8, 1.17 (95 % CI: 1.01-1.36) for parity 9, and 1.39 (95 % CI: 1.18-1.65) for parity 10. Additionally, they showed elevated rates of several maternal and neonatal outcomes, including placental abruption, large-for-gestational age (LGA) neonates, neonatal hypoglycemia, and neonatal seizures. Conversely, they exhibited decreased risk for other adverse maternal outcomes, including preterm deliveries, unplanned cesarean deliveries (CDs), vacuum-assisted delivery, and third- or fourth-degree perineal tears and small-for-gestational age (SGA) neonates. The associations with neonatal hypoglycemia, and neonatal seizure were correlated with the number of deliveries in a dose-dependent manner, demonstrating that each additional delivery was associated with an additional, significant impact on obstetrical complications. Conclusion: Our study demonstrates that parity 8-10 is associated with a significantly increased risk of PPH. Parity level > 5 correlated with increased odds of placental abruption, LGA neonates, neonatal hypoglycemia, and neonatal seizures. However, GMP women also demonstrated a reduced likelihood of certain adverse maternal outcomes, including unplanned cesarean, preterm deliveries, vacuum-assisted deliveries, SGA neonates, and severe perineal tears. These findings highlight the importance of tailored obstetrical care for GMP women to mitigate the elevated risks associated with higher parity.