Preterm delivery may increase future risks of chronic hypertension among women: JAMA

Preterm birth is an important issue in public health and is a major part of worldwide neonatal mortality and morbidity. Preterm delivery has been reported to have future cardiometabolic disorders in women, however its association with preterm delivery is unknown.

A nationwide cohort study by Casey Crump, MD, PhD and team revealed that preterm delivery was associated with significantly higher future risks of chronic hypertension. These associations remained elevated at least 40 years later and were not associated with maternal and familial factors.

The findings of the study are published in JAMA Cardiology.

The objective of the study was examine the long-term risks of chronic hypertension associated with preterm delivery in a large population-based cohort of women.

The study was a national cohort study including 2 195 989 women in Sweden with a singleton delivery from January 1, 1973, to December 31, 2015. New-onset chronic hypertension identified from primary care, specialty outpatient, and inpatient diagnoses using administrative data. Cox proportional hazards regression was used to compute hazard ratios (HRs) while adjusting for preeclampsia, other hypertensive disorders of pregnancy, and other maternal factors. Cosibling analyses were assessed for potential confounding by shared familial (genetic and/or environmental) factors.

The results of the study were

• Out of 351 189 of 2 195 989 women (16.0%) were diagnosed with hypertension. Within 10 years after delivery.

• The adjusted HR for hypertension associated with preterm delivery was 1.67, for extremely preterm it was 2.25, 1.85 for moderately preterm , 1.55 for late preterm, and 1.26 for early-term compared with full-term delivery.

• These risks decreased but remained significantly elevated at 10 to 19 years preterm vs full-term delivery adjusted HR, was 1.40; 95% CI, 1.36-1.44.

• 20 to 29 year adjusted HR, was 1.20; 95% CI, 1.18-1.23, and 30 to 43 years adjusted HR, was 95% CI, 1.12; 1.10-1.14 after delivery.

• These findings were not explained by shared determinants of preterm delivery and hypertension within families.

Crump, and team concluded that " n this large national cohort study, preterm delivery was associated with significantly higher future risks of chronic hypertension. These associations remained elevated at least 40 years later and were largely independent of other maternal and shared familial factors. Preterm delivery should be recognized as a lifelong risk factor for hypertension in women."

Reference:

Crump C, Sundquist J, Sundquist K. Preterm Delivery and Long-term Risk of Hypertension in Women. JAMA Cardiol. Published online October 13, 2021. doi:10.1001/jamacardio.2021.4127