Preterm delivery increases lifetime risk for ischemic heart disease
Women who delivered babies earlier than 37 weeks had increased risk for ischemic heart disease throughout their lifetime, researchers found.
“The results indicate that preterm delivery should now be recognized as an independent risk factor for ischemic heart disease in women across the life course,” Casey Crump, MD, PhD, professor and vice chair for research in the department of family medicine and community health and professor in the department of population health science and policy at Icahn School of Medicine at Mount Sinai, told Healio. “Cardiovascular risk assessment in women should routinely cover reproductive history including preterm delivery. Women with a history of preterm delivery may need early preventive actions to reduce other ischemic heart disease risk factors including obesity, physical inactivity and smoking, and long-term monitoring for timely detection and treatment of ischemic heart disease.”
Deliveries in Sweden
In the study published in the Journal of the American College of Cardiology, researchers analyzed data from 2,189,190 women within singleton deliveries in Sweden from 1973 to 2015. Information from the Swedish Medical Birth Registry was used to categorize women based on when they delivered: extremely preterm (22 to 27 weeks; n = 9,100), very preterm (28 to 33 weeks; n = 45,438), late preterm (34 to 36 weeks; n = 140,213), early term (37 to 38 weeks; n = 551,741), full term (39 to 41 weeks; n = 1,353,180) and post-term ( 42 weeks; n = 89,518).
“This was the first study to assess the potential influence of unmeasured familial factors on associations between preterm delivery and future maternal risk for ischemic heart disease,” Crump said in an interview.
Women were followed up for ischemic heart disease diagnosis from delivery through 2015 for a median of 22.1 years and a maximum of 43 years.
Ischemic heart disease was diagnosed in 2.3% of women during 47.5 million person-years of follow-up. These women had a median age at first delivery of 27.3 years and a median age of 57.4 years at diagnosis.
Ten years after delivery, the adjusted HR for ischemic heart disease was 2.47 in women with preterm delivery (95% CI, 2.16-2.82). Compared with women who delivered full-term babies, the HRs were 4.04 for women with extremely preterm deliveries (95% CI, 2.69-6.08), 2.62 for women with very preterm deliveries (95% CI, 2.09-3.29), 2.3 for women with late preterm deliveries (95% CI, 1.97-2.7) and 1.47 for women with early term deliveries (95% CI, 1.3-1.65).
After additional follow-up, the risk for ischemic heart disease declined but continued to be significantly elevated when women who delivered preterm babies were compared with those who delivered full-term babies. This was evident during follow-up at 10 to 19 years (adjusted HR = 1.86; 95% CI, 1.73-1.99), 20 to 29 years (adjusted HR = 1.52; 95% CI, 1.45-1.59) and 30 to 43 years (adjusted HR = 1.38; 95% CI, 1.32-1.45).
The association between preterm deliveries and ischemic heart disease was not related to shared environmental or genetic factors within families. More than one preterm delivery further increased the risk for ischemic heart disease.
“Additional follow-up of these women will be helpful to assess their ischemic heart disease risks at older ages,” Crump told Healio. “This study also was limited to Sweden and will need replication in other diverse populations to explore for possible variation of findings in different racial/ethnic groups.”
Generalizability to the U.S.
In a related editorial, Anne Marie Valente, MD, section chief of the Boston adult congenital heart and pulmonary hypertension program at Boston Children’s Hospital, and associate professor of medicine and pediatrics and director of the adult congenital heart disease senior fellowship at Harvard Medical School, and colleagues wrote, “It must be acknowledged that the United States has a different demographic and health care model compared with the Swedish population examined by Crump, et al. The United States has a higher proportion of preterm births with notable racial and ethnic disparities, and public health insurance coverage for mothers may end 60 days postpartum, making longer-term follow-up difficult for some women. Favorable changes in these policy-related issues around the childbearing years might also improve longer-term CVD risk stratification for women with concerning obstetrical histories and warrants study.”
For more information:
Casey Crump, MD, PhD, can be reached at firstname.lastname@example.org.