Twin Pregnancies Double Heart Disease Risk for Mothers in First Year After Birth: Study

New Delhi: Mothers of twins face double the risk of hospitalization due to heart disease in the first year after childbirth compared to those with singleton pregnancies, a new study reveals.

The risk is even greater for those who experienced high blood pressure conditions during pregnancy, according to research published in the European Heart Journal.

The study, led by Professor Cande Ananth from the Department of Obstetrics, Gynaecology, and Reproductive Sciences at Rutgers Robert Wood Johnson Medical School, New Jersey, analyzed data from 36 million hospital deliveries in the US Nationwide Readmissions Database from 2010 to 2020.

Professor Ananth explained, "The rate of twin pregnancies worldwide has risen in recent decades, driven by fertility treatments and older maternal ages. Previous studies have shown no long-term increased risk of cardiovascular disease when following people with twin pregnancies for decades after delivery. However, this is counterintuitive to what we observe clinically when caring for patients with twin pregnancies. Given the unacceptably high rate of maternal mortality in the first year after birth due to cardiovascular disease, we wanted to examine whether twin pregnancies increase this risk."

The study categorized pregnant patients into four groups: those with twins and normal blood pressure, those with twins and hypertensive disease of pregnancy, those with singleton pregnancies and normal blood pressure, and those with singleton pregnancies and hypertensive disease of pregnancy.

The researchers focused on hospital readmissions within a year of childbirth for cardiovascular diseases, such as heart attack, heart failure, or stroke.

The findings revealed that mothers of twins had higher hospital readmission rates for cardiovascular disease (1,105.4 per 100,000 deliveries) compared to those with singleton pregnancies (734.1 per 100,000 deliveries).

Compared to singleton pregnancies with normal blood pressure, mothers of twins with normal blood pressure were nearly twice as likely to be hospitalized for cardiovascular disease. For those with twins who had high blood pressure during pregnancy, the risk was more than eight times higher.

However, one year after birth, overall mortality rates, including deaths from heart disease, were higher among singleton pregnancies with high blood pressure conditions than among those with twins who had similar conditions.

This suggests that while twin mothers face greater short-term risks, singleton mothers with high blood pressure may have other pre-existing cardiovascular risk factors affecting their long-term health.

Dr. Ruby Lin, a maternal-fetal medicine fellow at Rutgers Robert Wood Johnson Medical School and the study's lead author, emphasized, "The maternal heart works harder for twin pregnancies than for singleton pregnancies, and it takes weeks for the maternal heart to return to its pre-pregnancy state. People with twin pregnancies should be aware of the short-term increase in cardiovascular disease complications in the first year after birth, even if they had a pregnancy that was not complicated by high blood pressure conditions, such as pre-eclampsia."

She added, "For patients undergoing fertility treatments, especially those with other cardiovascular risk factors such as older age, obesity, diabetes, high blood pressure, or heart disease, it is important to be aware that twin pregnancies may increase cardiovascular disease complications in the short term. Given these higher risks, health care providers and health insurance companies should continue to provide follow-up for up to a year after birth for high-risk pregnancies such as twin pregnancies."

Dr. Kevin Quadros, Consultant Obstetrician and Gynecologist at Holy Family Hospital, Bandra, Mumbai, commented, "This study reinforces the importance of close monitoring of twin pregnancies both during and after childbirth. Twin pregnancies naturally place a higher physiological burden on the mother's heart, and with India's rising rates of fertility treatments, these findings hold significant clinical relevance for our population."

In an accompanying editorial, Dr. Katherine Economy from Brigham and Women's Hospital, Boston, and colleagues highlighted the importance of understanding cardiovascular risk factors during pregnancy. "Greater understanding of risk factors for cardiovascular disease (CVD) during pregnancy is of substantial interest in light of current maternal morbidity rates in the U.S. and data revealing that ~33% of pregnancy-related deaths are attributable to cardiovascular events," they wrote.

They concluded, "We must embrace the fourth trimester (12 weeks after delivery) as a critical time period to make impactful changes that will influence long-term cardiovascular health. Collaboration among obstetricians, cardiologists, and other medical specialists is essential to address the crisis of maternal mortality and to reduce postpartum complications, including improving the accessibility and quality of postpartum care."