Pregnancy health, mortality link particularly pronounced in black women

Over 50 years of data support the link between pregnancy complications and premature death, but solutions remain elusive.

Pregnancy complications are associated with later mortality risks, and this association appears to be even stronger in black women, according to more than 50 years of follow-up data from the Collaborative Perinatal Project.

The findings complement other research findings that a decades of connection between conditions such as hypertensive disorders of pregnancy, prematurity and gestational diabetes with adverse outcomes, but the study, launched in 1959, goes a step further by highlighting deep-rooted racial differences that have not changed in subsequent years.

“Our findings convey and support the message that promoting healthy longevity should begin early, beginning with a healthy pregnancy,” commented senior author Cuilin Zhang, MD, PhD (Yong Loo Lin School of Medicine, National University of Singapore) in an email to TCTMD. “This is especially true in light of additional data implicating the intergenerational health implications 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 validates everything we know.”

What’s perhaps “most disturbing” is that even 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 high blood pressure rates in black women, even back then, chronic high blood pressure was twice as common in black women as in white women. It confirms what we know and unfortunately we haven’t made much progress there.”

More than 50 years of data

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

Overall mortality was higher in black participants than in white participants (41% vs. 37%), as was the incidence of preterm birth (20% vs. 10%).

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

  • Spontaneous preterm labour: HR 1.07 (95% CI 1.03-1.1)
  • Premature rupture of membranes: HR 1.23 (95% CI 1.05-1.44)
  • Labor Induced: HR 1.31 (95% CI 1.03-1.66)
  • Caesarean section before birth vs. full-term birth: 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 the patients were black or white in relation to both preterm births (P = 0.009) and hypertensive pregnancy disorders (P = 0.05). In addition, preterm labor was associated with a greater risk of mortality over time for black women (adjusted HR 1.64; 95% CI 1.10-2.46) compared to white women (adjusted HR 1.29; 95% CI 0, 97-1.73).

“We need to find out why”

The American Congress of Obstetricians and Gynecologists already supports a “warm transfer” 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, patients become preoccupied, don’t follow up, and eventually get lost in the system. What can complicate matters further is that many patients who experience a problem during pregnancy, such as

Bello cited another common situation where a patient never understood the seriousness of a complication she was experiencing at the time. “They may have been told, but so much happens at the time of birth that sometimes it gets lost in the immediate concerns of ‘how am I doing?’, ‘how is my baby?’, pain and wound care,” she said .

“It’s not just about collaboration between doctors, nurses and the care team, we also need to educate patients that this is something that requires long-term follow-up if they leave the hospital or risk in their postpartum visit” , emphasized Bello.

However, this gets even more complicated when one considers the racial differences found in this study. “It’s annoying that we don’t influence the disparities [and] that they persist over time. . . . Obviously, if we look at the black maternal mortality crisis in this country, it has a long legacy and will not be solved overnight, but we really need to start working to reduce it. It’s not enough to just say, “Oh look, this is where we found black women have lower scores. We need to figure out why and fix it.”

In the future, she would like to see more studies looking at changing risk factors after poor pregnancy outcomes, particularly with regard to more aggressive lipid lowering and the role that antiplatelet or vascular-modifying drugs might play for some. “We just don’t have the data,” Bello said.

Zhang also said more research is needed in “other racial/ethnicity groups, such as Asians and Hispanics, where limited data is available.”

Pregnancy health, mortality link particularly pronounced in black women

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