Delivery at 39 weeks may optimize maternal, neonatal outcomes in mild chronic hypertension
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Key takeaways:
- Planned early-term delivery did not improve maternal outcomes for women with mild chronic hypertension.
- Early delivery was associated with increased risks for neonatal complications, such as hypoglycemia.
Women with mild chronic hypertension induced at 37 weeks’ gestation saw no reduction in adverse maternal outcomes compared with women delivered at 39 weeks, but did experience increases in some neonatal complications, data show.
“The current national clinical guidance is to deliver patients with chronic hypertension between 37 and 39 weeks, so it is difficult to know as a clinician what that ‘best’ timing would be when we are talking with patients about when we would recommend induction,” Torri D. Metz, MD, MS, associate professor of maternal-fetal medicine and vice chair of research in obstetrics and gynecology at the University of Utah, told Healio. “The window is pretty wide. We wanted to see if there was an ideal gestational age to optimize maternal and neonatal outcomes for pregnant people who had milder hypertension.”
The findings were from a planned secondary analysis of the Chronic Hypertension and Pregnancy (CHAP) trial, which evaluated whether it is beneficial and safe to prescribe blood pressure medication to pregnant women with mild chronic hypertension, defined as BP less than 160/100 mm Hg. As Healio previously reported, CHAP researchers found treating mild chronic hypertension during pregnancy to a BP goal of less than 140/90 mm Hg reduced adverse pregnancy outcomes and did not impair fetal growth.
The substudy of 1,417 participants with mild chronic hypertension included 21.5% with a new diagnosis in pregnancy and 78.5% with known preexisting hypertension. The primary maternal composite outcome included death, serious morbidity (heart failure, stroke, encephalopathy, myocardial infarction, pulmonary edema, ICU admission, intubation, renal failure), preeclampsia with severe features, hemorrhage requiring blood transfusion or abruption. The primary neonatal outcome included fetal or neonatal death, respiratory support beyond oxygen mask, Apgar score less than 3 at 5 minutes, neonatal seizures or suspected sepsis. Secondary outcomes included intrapartum cesarean birth, length of stay, NICU admission, respiratory distress syndrome, transient tachypnea of the newborn and hypoglycemia. Researchers compared outcomes of women with a planned delivery vs. those expectantly managed at each gestational week.
“When the CHAP trial was initiated, we came up with some other research questions that we wanted the data to answer and this was one of them,” Metz said during an interview. “We took the information that we had from the participants in the CHAP trial and then analyzed it to determine if delivering women during different gestational age windows improved their outcomes.”
In adjusted models, researchers observed no association between planned delivery and the primary maternal or neonatal composite outcomes in any gestational age week compared with expectant management.
The researchers did observe an increased risk for respiratory distress syndrome in neonates delivered at 37 weeks’ gestation vs. expectant management, with an adjusted OR of 2.7 (95% CI, 1.4-5.22). Planned early delivery was also associated with higher rates of neonatal hypoglycemia vs. expectant management, with adjusted ORs of 1.97 for planned delivery at 37 weeks (95% CI, 1.27-3.08) and 1.82 for planned delivery at 38 weeks (95% CI, 1.06-3.1).
Metz said the findings are similar to what researchers have observed in related work.
“We know that when we are delivering patients in what we call the early-term period, we are balancing the need to deliver them because of risk for stillbirth or maternal risk against what we know is a slightly higher risk for these neonatal complications,” Metz told Healio. “What is notable here is we did not see that we were helping the mothers [with early delivery] but increasing risk for the neonates. What we concluded is that in patients with mild high BP during pregnancy, where everything has been going OK up until early term, potentially waiting until 39 weeks could optimize outcomes for the neonate without putting the mother at increased risk.”
Metz noted researchers did not observe an increased risk for cesarean delivery with induced labor at any gestational age, indicating that when used appropriately, patients can have a reasonable expectation for vaginal delivery with induction.
For more information:
Torri D. Metz, MD, MS, can be reached at torri.metz@hsc.utah.edu.