Perinatal outcomes of pregnancies complicated by prenatally resolved fetal growth restriction

OBJECTIVE: Fetal growth restriction (FGR) is associated with an increased risk of adverse maternal and perinatal outcomes. 1 - 3 In our experience, prenatal sonographic resolution of FGR commonly occurs. Considering that maternal and perinatal outcomes in these pregnancies have not been widely studied, we compared the outcomes of these pregnancies to those without FGR and those with persistent FGR. 4 STUDY DESIGN: This retrospective cohort study included singleton pregnancies in women > 18 years old delivering at a single institution between January 1, 2020 and December 31, 2022. Pregnancies were excluded for multiple gestation, fetal anomaly, aneuploidy, genetic syndrome, or congenital infection with cytomegalovirus, syphilis, toxoplasmosis, or varicella. We first identified eligible pregnancies with FGR initially diagnosed > 26 weeks gestation by fetal abdominal circumference (AC) and/or estimated fetal weight (EFW) below the tenth percentile for gestational age. 3,5 We employed this definition of FGR to re fl ect current clinical guidance and our institution ' s practice, recognizing that this approach could be associated with including constitutionally small fetuses and that some clinicians may recommend the presence of fetal growth deceleration to diagnose FGR. 6 Both the fetal AC and EFW needed to recover to > 10th percentile for gestational age to move a fetus into the resolved FGR group. The referent group comprised the next 2 consecutive ultrasound patients after each index FGR pregnancy that did not demonstrate FGR but otherwise met inclusion criteria. The primary outcome was a composite of 1 or more of the following: fetal or neonatal death, seizures, respiratory distress syndrome, necrotizing enterocolitis, intraventricular hemorrhage, sepsis, neonatal intensive care admission > 24 hours, hypoglycemia requiring treatment, thrombocytopenia, transient tachypnea of the newborn, hyperbilirubinemia, and 5 -minute Apgar score < 7. Secondary outcomes included birthweight, birthweight percentile < 10%, 7 cesarean delivery, and operative vaginal delivery. The institutional review board approved this study with an exemption because it comprised deidenti fi ed existing data. A sample size calculation demonstrated that 97 subjects with persistent FGR, 97 subjects with resolved FGR, and 194 referent subjects would provide 80% power to detect a difference ( P < .05) among subgroups, assuming primary outcome frequencies of 30%, 22%, and 14%, respectively. 1,2,8 Differences among the 3 FGR subgroups were analyzed using chi-square test, Fisher ' s exact test (categorical data), analysis of variance (normally distributed interval data) or KruskalWallis test (nonnormally distributed interval data), as appropriate. If the three-way comparison was signi fi cant, we performed post hoc pairwise comparisons and interpreted signi fi cance after Bonferroni ' s correction for multiple comparisons. We calculated odds ratios for the primary outcome using logistic regression and adjusted for statistically and clinically signi fi cant covariates. RESULTS: One hundred eighty-one referent, 81 resolved FGR, and 97 persistent FGR pregnancies were included. The primary outcome occurred signi fi cantly more frequently in both the resolved FGR (odds ratio [OR], 1.9; 95% con fi dence interval [CI], 1.1 - 3.5; P = .026) and persistent FGR (OR, 2.8; 95% CI, 1.7 - 4.9; P < .001) groups. After adjusting for oligohydramnios, chronic hypertension, opioid use disorder, and maternal age, the fi ndings for resolved and persistent FGR persisted with adjusted OR (aOR), 2. 04; 95% CI, 1.11 - 3.74 ( P = .022) and aOR, 2.83; 95% CI, 1.58 - 5.07 ( P < .001), respectively. The Table shows fi ndings for individual components of the primary and secondary outcome. Additional data are available from the corresponding author on request addressing identification of possible covariates, maternal demographics, maternal and obstetrical comorbidities, and pregnancy ultrasoundfindings, respectively, by FGR group. CONCLUSION: Neonates with prenatally resolved FGR remain at increased risk for adverse perinatal outcomes. This fi nding may inform the anticipated level of neonatal care and planned delivery setting. Larger studies are warranted to assess the interval and duration of antepartum fetal surveillance, as well as the role of umbilical artery Doppler velocimetry in stratifying risk in the resolved FGR population.