Severe Maternal Morbidity at First Birth Linked to Lower Subsequent Birth Rates

Women who experienced severe maternal morbidity with their first birth were less likely to have more children, a retrospective Swedish population-based cohort study suggested.

Among nearly 36,800 women, those with any severe maternal morbidity conditions during their first birth had a lower incidence rate of subsequent births compared with those without such conditions (136.6 vs 182.4 per 1,000 person-years; adjusted HR 0.88, 95% CI 0.87-0.89), reported Eleni Tsamantioti, MD, MMedSc, of the Karolinska Institute in Stockholm, and colleagues in JAMA.

The probability of subsequent birth was substantially lower for women who experienced certain severe maternal morbidity conditions, including:

• Severe uterine rupture (aHR 0.48, 95% CI 0.27-0.85)
• Cardiac complications (aHR 0.49, 95% CI 0.41-0.58)
• Cerebrovascular accident (aHR 0.60, 95% CI 0.50-0.73)
• Severe mental health conditions (aHR 0.48, 95% CI 0.44-0.53)

Sibling analyses confirmed that these associations were not influenced by familial confounding. Those who experienced sepsis or anesthesia complications did not have lower probability of subsequent birth.

A sensitivity analysis showed that women who jointly experienced severe maternal morbidity and adverse neonatal outcomes — including stillbirth, very preterm birth, or major malformation — had lower subsequent birth rates (aHR 0.81, 95% CI 0.77-0.84) compared with those with severe maternal morbidity but not adverse neonatal outcomes (aHR 0.89, 95% CI 0.88-0.91).

This study “aimed to quantify the association between experiencing SMM [severe maternal morbidity] in the first birth and probability and timing of a subsequent birth,” Tsamantioti and team wrote, noting that trauma during pregnancy and delivery can shape reproductive decisions and contribute to persistent health issues, including reproductive challenges.

“Adequate reproductive counseling and improved monitoring and antenatal care are crucial for women with a history of SMM,” they concluded.

In an accompanying editorial, Anders Husby, MD, PhD, and Heather A. Boyd, PhD, both of the Statens Serum Institute in Copenhagen, noted that the findings were not particularly surprising since severe maternal morbidity events can make it more difficult to become pregnant or safely carry a pregnancy to completion. Moreover, for the women who do, the risk of having recurrent severe maternal morbidity is increased.

However, this study “did not address the influence of severe maternal morbidity on future childbearing in parous women, which may restrict how the findings can be applied to women who experienced severe maternal morbidity in second or later pregnancies.”

“It might be beneficial to focus future research on developing evidence-based, cross-specialty tools to help women who have experienced severe morbidity during pregnancy in making future reproductive decisions,” they wrote.

This study included 1,046,974 Swedish women who had their first birth between 1999 and 2021. Severe maternal morbidity was identified among all deliveries at 22 weeks of gestation or later, including complications within 42 days of delivery, from the Swedish Medical Birth Register and National Patient Register.

Among women who had experienced at least one severe maternal morbidity event in their first birth, median age was 29, median body mass index (BMI) was 24, and 7% had used in vitro fertilization or intracytoplasmic sperm injection to conceive.

In general, women who experienced severe maternal morbidity in their first birth were more likely to be older, shorter, have a higher BMI, have pregestational hypertension and diabetes, and have used assisted reproductive technology. They also had a higher frequency of multifetal pregnancies, induced labor, cesarean delivery, and preterm birth.

Severe maternal morbidity was defined as a composite of life-threatening events occurring during pregnancy, delivery, or up to 42 days postpartum, including severe preeclampsia, severe hemorrhage, severe uterine rupture, surgical complications, hysterectomy, sepsis, cerebrovascular accident, cardiac complications, and severe mental health conditions, among others.

Tsamantioti and colleagues noted that their study focused on first and second recorded deliveries, which could have limited the generalizability of results to higher-order parities. They also didn’t delve into the underlying mechanisms of reduced probability of a subsequent birth.

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