Pregnancy Health, Mortality Link Especially Pronounced in Black Women

Pregnancy complications are linked to later mortality risks and that relationship appears to be even stronger in Black women, according to more than 50 years of follow-up data from the Collaborative Perinatal Project.

The results add to other research detailing a decades-long connection between conditions like hypertensive disorders of pregnancy, preterm delivery, and gestational diabetes with adverse outcomes, but the study—launched in 1959—goes one step further by highlighting entrenched racial disparities that haven’t budged in the ensuing years.

“Our findings further convey and support the message that promoting healthy longevity should start early, start from a healthy pregnancy,” senior author Cuilin Zhang, MD, PhD (Yong Loo Lin School of Medicine, National University of Singapore), commented in an email to TCTMD. “This is particularly true given additional data implicating the intergenerational adverse health impacts of common pregnancy complications.”

Natalie Bello, MD, MPH (Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA), who was not involved in the analysis, said “it confirms everything we've known.”

Perhaps what’s “most upsetting” is that even back in the 1950s and 60s, when the women were enrolled in the study, “there were these stark racial disparities in maternal outcomes,” she told TCTMD. “If you look at the rates in Black women's rates of hypertension, even back then chronic hypertension was twice as common in Black women compared to white women. It reinforces what we've known and, unfortunately, we haven't made much progress there.”

More Than 50 Years of Data

For the study, published online last week ahead of print in Circulation, Stefanie N. Hinkle, PhD (University of Pennsylvania, Philadelphia), Zhang, and colleagues included 46,551 participants, 45% of whom were Black, who had a median duration of 52 years of data between pregnancy and death or censoring. The patients were enrolled in the Collaborative Perinatal Project, which enrolled pregnant women from 12 US centers between 1959 and 1966, and follow-up data were collected through 2016.

Overall, mortality was higher for Black than white participants (41% vs 37%), as was the incidence of preterm delivery (20% vs 10%).

All-cause mortality over time was associated with the following pregnancy complications after adjustment for age, prepregnancy body mass index, smoking, race and ethnicity, previous pregnancies, marital status, income, education, previous medical conditions, site, and year:

• Preterm spontaneous labor: HR 1.07 (95% CI 1.03-1.1)
• Premature rupture of membranes: HR 1.23 (95% CI 1.05-1.44)
• Induced labor: HR 1.31 (95% CI 1.03-1.66)
• Prelabor cesarean vs full-term delivery: HR 2.09 (95% CI 1.75-2.48)
• Gestational hypertension: HR 1.09 (95% CI 0.97-1.22)
• Preeclampsia or eclampsia: HR 1.14 (95% CI 0.99-1.32)
• Superimposed preeclampsia or eclampsia: HR 1.32 (95% CI 1.20-1.46)
• Gestational diabetes/impaired glucose tolerance: HR 1.14 (95% CI 1.00-1.30)

There was an interaction between whether patients were Black or white with regard to both preterm delivery (P = 0.009) as well as hypertensive disorders of pregnancy (P = 0.05). Also, preterm labor was associated with a greater risk for mortality over time for Black (adjusted HR 1.64; 95% CI 1.10-2.46) compared with white women (adjusted HR 1.29; 95% CI 0.97-1.73).

‘We Need to Figure Out Why’

The American Congress of Obstetricians and Gynecologists already supports a “warm handoff” of patients with pregnancy complications to either cardiology or primary care, depending on the complexity of the case, Bello explained. But what often happens is that over time, the patients get busy, don’t follow up, and eventually get lost in the system. What also can complicate matters is that a lot of patients who have an issue during pregnancy, like gestational hypertension, see resolution of their symptoms in the postpartum period and assume the problem also has disappeared.

Bello cited another common situation, in which a patient never understood how serious of a complication she experienced at the time. “They may have been told, but there's so much going on at the time of delivery that it can sometimes get lost in the immediate concerns of ‘How am I doing?’, ‘How is my baby?’, pain, and wound care,” she said.

“It's not just the cooperation between physicians, nurse practitioners, the care team, but also we need to educate patients when they leave the hospital or in their postpartum visit that this is something that requires long-term follow-up and we can modify your risk,” Bello stressed.

That gets even more complicated when you factor in the racial differences seen in this study, however. “It's upsetting that we're not making any impact on the disparities [and] that they're persisting over time. . . . When we look at the Black maternal mortality crisis at this country, it has obviously a long legacy and it's not going to get fixed overnight, but we really need to start working to reduce it. It's not enough to just say, ‘Oh look, here we've found that Black women are having worse outcomes.’ We need to figure out why that is and fix them.”

Going forward, she would like to see more studies look at risk-factor modification after adverse pregnancy outcomes, especially with regard to more aggressive lipid-lowering and what role antiplatelet agents or vascular-modifying medications might play for some. “We just don't have the data,” Bello said.

Zhang, too, said more research is needed in “other race/ethnicity groups such as Asian and Hispanic where limited data are available.”