Twin Pregnancy Doubles Risk of Heart Disease in Mothers, Study Finds

The research published in the European Heart Journal revealed that mothers of twins are at an elevated risk of hospitalization due to heart disease in the first year after birth.

The risk is also higher for those who have high blood pressure (hypertension) during pregnancy, a condition known as preeclampsia.

The study was led by researchers from Rutgers University in the U.S. In recent decades, the rate of twin pregnancies has increased worldwide, driven by fertility treatments and older maternal ages, says Professor Ananth.

Looking into past studies that have shown a long-term increase in cardiovascular diseases, researchers have observed people with twin pregnancies after delivery for decades. ⁽¹⁾

Dr. Ruby Lin, lead author and maternal-fetal medicine fellow at Rutgers Robert Wood Johnson Medical School, explains that the maternal heart works harder during a twin pregnancy than in a singleton pregnancy. Returning to a normal (pre-pregnancy) state takes several weeks.

The researchers were struck by the high mortality rate of pregnant mothers in the first year after delivery due to cardiovascular risks. Because of this, they examined whether twin pregnancies increase the risk of cardiovascular disease.

Dr. Ruby Lin also explained that patients undergoing fertility treatments, as well as those with cardiovascular risk factors such as obesity, older age, diabetes, heart disease, and high blood pressure, should be aware that twin pregnancies can increase short-term cardiovascular complications.

Keeping this in mind, healthcare providers and insurance companies must continue providing services for up to a year after birth for twin pregnancies, which are at higher risk.

How Does the Analysis Assess Risk?

The study categorized pregnant women into four groups:

1. Mothers with twins and normal blood pressure

2. Mothers with twins and hypertensive disease of pregnancy

3. Mothers with singleton pregnancies and normal blood pressure

4. Mothers with singleton pregnancies and hypertensive disease of pregnancy

The research focused on hospital readmissions within a year of childbirth for cardiovascular disease (CVD) such as heart failure, heart attack, or stroke.

The analysed data in the research study examined around 36 million hospital deliveries from 2010 to 2020 in the US.

The outputs have showcased a more increased proportion of readmissions for cardiovascular disease(CVD) within a year of delivering women with twins (1,105.4 per 100,000 deliveries) than women giving birth to single (734.1 per 100,000 deliveries). ⁽³⁾

Pregnancy provides a unique window into cardiovascular health (CVH), as obstetric complications and adverse pregnancy outcomes can predict cardiovascular disease.

There is a particular knowledge gap regarding twin pregnancies in pregnancy and cardiovascular disease research.

Twin pregnancies account for 31 per 1,000 births (3.1%), with about two-thirds conceived spontaneously and the remaining one-third conceived with the help of assisted reproductive technologies (ART), such as in-vitro fertilization (IVF) or ovulation induction therapies.

Increased Risk Factors for Spontaneous Twin Conception

• Increased body mass index (BMI)

• Increased maternal age

• Family history of multiple gestations

• Certain racial groups have a higher incidence of twins

For example, spontaneous twinning is more common among Black Americans. In Nigeria, the twinning rate is 50 per 1,000 births.

To address the knowledge gap between pregnancy and cardiovascular disease, new data from the Nationwide Readmissions Database (NRD) highlighted differences in the one-year risk of cardiovascular disease hospitalizations and mortality between twin and singleton pregnancies, both with and without hypertensive disease of pregnancy.

Limitations of Assisted Reproductive Technology (ART)

The study results reinforce long-standing obstetrical beliefs that multiple gestations carry higher risks due to:

• Increased maternal, obstetric, and fetal risks

• Higher rates of structural and genetic anomalies

• Fetal growth restriction

• Prematurity

• Hemorrhage

• Hypertensive disorders of pregnancy (HDP)

• Gestational diabetes

• Increased risk of cesarean delivery and associated complications

Compared to singleton pregnancies, HDP is more frequently associated with twin pregnancies.

Twin and triplet neonates are more likely to require neonatal intensive care and experience complications such as:

• Increased risks of respiratory, gastrointestinal, hematological, infectious, and cardiovascular morbidity

• Neurodevelopmental delays

The American College of Obstetrics and Gynecology has recommended increased maternal and fetal surveillance for twin and higher-order gestations, including:

• Close monitoring of blood pressure (BP)

• Maternal weight gain

• Maternal nutrition

• Fetal well-being

People undergoing ART are advised to have a preconception consultation with a maternal-fetal medicine specialist, medical subspecialists, or internal medicine experts.

Mothers of twins with normal blood pressure were about twice as likely to be hospitalized with cardiovascular disease (CVD) compared to mothers with singleton pregnancies and normal blood pressure.

The study showed that mothers of twins who developed high blood pressure during pregnancy faced more than an eightfold increase in risk.

One year after delivery, deaths from any cause, including heart disease, were higher among mothers of singleton pregnancies who had high blood pressure compared to mothers of twins with high blood pressure. This suggests that mothers of twins may have a decreased long-term risk of cardiovascular disease, while mothers of singleton pregnancies may have pre-existing cardiovascular risk factors.

Dr. Kevin Quadros, a consultant obstetrician and gynecologist at Holy Hospital, Bandra, Mumbai, commented in the Health Dialogues blog: ⁽²⁾

"It's very important to closely monitor 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 the European Heart Journal, Dr. Katherine Economy from Brigham and Women's Hospital, Boston, and colleagues emphasized the importance of understanding cardiovascular risk factors during pregnancy. They stated:

"A strong understanding of risk factors for CVD during pregnancy is of significant interest in light of existing maternal morbidity rates in the U.S. and data indicating that ~33% of pregnancy-related deaths are attributable to cardiovascular events." ⁽¹⁾

Key Interventions to Improve Maternal Health Outcomes

1. Implementing multidisciplinary care for women with high-risk comorbidities before conception, during pregnancy, postpartum, and beyond

2. Addressing structural racism and social determinants of health

3. Introducing hospital-wide safety protocols with trained teams

4. Providing patient education on early warning signs of pregnancy-related medical complications

5. Regionalizing maternal levels of care so that high-risk patients deliver at facilities with specialized care teams ⁽⁴⁾

These interventions emphasize the need for further efforts to reduce maternal and pregnancy-related mortality and morbidity. Recognizing the "fourth trimester" (12 weeks postpartum) as a crucial period is essential for making impactful changes that will influence long-term cardiovascular health. Collaborative efforts among obstetricians, cardiologists, and other medical specialists are needed to address maternal mortality and improve postpartum care accessibility and quality. ⁽¹⁾

References

1. Williams, Alexandria F., Anne M. Valente, and Katherine E. Economy. "Double Double, Future Trouble? Opportunities for Cardio-obstetric Collaboration to Reduce Future Cardiovascular Events following Twin Pregnancies." European Heart Journal. Accessed February 4, 2025. https://doi.org/10.1093/eurheartj/ehaf064.

2. Verma, Rishika. "Twin Pregnancies Double Heart Disease Risk for Mothers in First Year After Birth: Study." Health Dialogues, February 3, 2025. Accessed February 4, 2025. https://health.medicaldialogues.in/health-topics/women-health/twin-pregnancies-double-heart-disease-risk-for-mothers-in-first-year-after-birth-study-142624.

3. Hauspurg, Alisse, Wendy Ying, Carl A. Hubel, Erin D. Michos, and Pamela Ouyang. "Adverse Pregnancy Outcomes and Future Maternal Cardiovascular Disease." Clinical Cardiology 41, no. 2 (2018): 239–246. https://pubmed.ncbi.nlm.nih.gov/31575778/.

4. Collier, Ai-ris Y., and Rose L. Molina. "Maternal Mortality in the United States: Updates on Trends, Causes, and Solutions." Neoreviews 20, no. 10 (2019): e561–e574. Accessed February 4, 2025. https://publications.aap.org/neoreviews/article-abstract/20/10/e561/92014/Maternal-Mortality-in-the-United-States-Updates-on.
   

(Input from various sources)

(Rehash/Dr Lakshmisahithi Tanneru/MSM)