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Black women have fewer maternal and neonatal complications in pregnancies conceived via in vitro fertilization

      Objective

      Increased adverse maternal and neonatal outcomes are well-documented in non-Hispanic black compared to non-Hispanic white women in the United States. These include an increase in infant mortality, low birthweight, preterm deliveries, gestational diabetes mellitus, and hypertensive disorders of pregnancy.
      • Battarbee A.N.
      • Sinkey R.G.
      • Harper L.M.
      • Oparil S.
      • Tita A.T.N.
      Chronic hypertension in pregnancy.
      ,
      • Creanga A.A.
      • Bateman B.T.
      • Kuklina EV.v.
      • Callaghan W.M.
      Racial and ethnic disparities in severe maternal morbidity: a multistate analysis, 2008–2010.
      Although these disparities are often attributed to differences in economic and social determinants of health, they were found to be persistent even after adjusting for these factors, suggesting possible biological bases.
      • Howell E.A.
      Reducing disparities in severe maternal morbidity and mortality.
      ,
      • Slattery M.M.
      • Morrison J.J.
      Preterm delivery.
      Pregnancies conceived by means of in vitro fertilization (IVF) represent a unique population, often with appropriate prepregnancy medical care, access to prenatal care, and overall higher socioeconomic status. We set out to assess whether the racial disparities described in the general population exist in this unique population of pregnancies following IVF in the United States.

      Study Design

      We performed a retrospective analysis of the Centers for Disease Control and Prevention’s (CDC) natality database (2016–2018) of births conceived via IVF in women who self-identified as non-Hispanic Black (Black) or non-Hispanic White (White). The Pearson’s chi-square test was used to compare several pregnancy and neonatal outcomes among women of both races. Multivariate logistic regression adjusted the outcomes for potential confounders, including preexisting health determinants such as maternal age, body mass index, parity, pregestational diabetes mellitus and hypertension, smoking status, and previous preterm deliveries and social determinants such as insurance status and level of education. The results are displayed as adjusted odds ratios (aOR) with 95% confidence intervals (CI). Statistical significance was set as a P value <.05. Institutional review board approval was not required, as the deidentified data are publicly available through a data use agreement.

      Results

      A total of 8,485,531 births of non-Hispanic Black and White women were recorded in the US natality database during the study period. Of those, 1,788,197 (21%) were of Black women, and 6,697,334 (79%) were of White women. Overall 116,684 pregnancies were conceived via IVF (1.4%). Only 7,721 (0.4%) pregnancies of Black women were conceived via IVF compared with 108,963 (1.6%) pregnancies of White women (Table 1) . After adjusting for confounders, the pregnancies of Black women conceived via IVF had a lower risk of gestational diabetes mellitus (aOR, 0.8; 95% CI, 0.7–0.9), hypertensive disorders of pregnancy (aOR, 0.8; 95% CI, 0.7–0.9), and eclampsia (aOR, 0.9; 95% CI, 0.9–1) than White women (Table 2). Immediate and prolonged neonatal ventilation rates were also decreased (aOR, 0.7 and 0.75; 95% CI, 0.7–0.8 and 0.6–0.8; respectively) despite increased rates of a 5-minute Apgar score lower than 7 (aOR, 1.3; 95% CI, 1.1–1.5). No differences were found in the rates of preterm deliveries, maternal intensive care unit admissions, gravid hysterectomies, neonatal intensive care unit admissions, and administration of antibiotics to the newborn (P>.05).
      Table 1Baseline demographic criteria of non-Hispanic White and non-Hispanic Black women who gave birth in the United States between 2016 and 2018
      DemographicsNon-Hispanic Black

      N=7,721
      Non-Hispanic White

      N=108,963
      Maternal age (y)
       <204 (0.1)13 (0.01)
       20–2492 (1.2)920 (0.8)
       25–29660 (8.6)11,338 (10.4)
       30–341,976 (25.6)38,101 (35)
       35–392,679 (34.7)37,706 (34.6)
       ≥402,310 (29.9)20,885 (19.2)
      Body mass index
       Underweight <18.580 (1)2,230 (2.1)
       Normal 18.5–24.92,129 (27.6)55,097 (50.6)
       Overweight 25.0–29.92,642 (34.2)27,418 (25.2)
       Obesity index >30.02,870 (37.2)24,218 (22.2)
      Total birth order
       12,592 (33.6)39,461 (36.2)
       22,025 (26.2)31,560 (29)
       3+3,104 (40.2)37,942 (34.8)
      Payment
       Medicaid928 (12)3,853 (3.5)
       Private insurance6,400 (82.9)104,063 (95.5)
       Self-pay393 (5.1)1,047 (1)
      Education
       Less than high school101 (1.3)488 (0.5)
       High school graduate1,691 (21.9)16,290 (15)
       College3,090 (40)50,268 (46.1)
       Masters degree or higher2,839 (36.8)41,917 (38.5)
      Pregestational diabetes mellitus173 (2.2)957 (0.9)
      Chronic hypertension664 (8.6)3,387 (3.1)
      Previous preterm delivery379 (4.9)3,937 (3.6)
      Smoking35 (0.5)543 (0.5)
      Data are presented as number (percentage).
      Bar-El. Black women have fewer maternal and neonatal complications in pregnancies conceived via in vitro fertilization. Am J Obstet Gynecol 2022.
      Table 2Maternal and neonatal outcomes risk-adjusted for maternal age, body mass index, parity, insurance status, education, pregestational diabetes mellitus and hypertension, smoking status, and previous preterm deliveries
      OutcomesNon-Hispanic Black

      N=7,721
      Non-Hispanic White

      N=108,963
      Adjusted odds ratio95% confidence interval
      Maternal/pregnancy outcomes
       Gestational diabetes mellitus866 (11.2)10,420 (9.6)0.8(0.7–0.9)
      Significant difference with P value <.05.
       Hypertensive disorders of pregnancy1,067 (13.8)14,803 (13.6)0.8(0.7–0.9)
      Significant difference with P value <.05.
       Eclampsia57 (0.7)488 (0.5)0.9(0.9–1.0)
      Significant difference with P value <.05.
       Preterm delivery2,628 (34)26,534 (24.4)0.9(0.8–1.1)
       Ruptured uterus5 (0.1)48 (0.04)1.3(0.3–6.0)
       Gravid hysterectomy31 (0.4)207 (0.2)1.2(0.6–2.5)
       Maternal admission to intensive care unit76 (1.0)451 (0.4)1.3(0.8–2.1)
       Multiple gestations2,393 (31)28,115 (25.8)0.7(0.6–0.7)
      Significant difference with P value <.05.
      Neonatal outcomes
       Low 5-min Apgar381 (4.9)2,890 (2.7)1.3(1.1–1.5)
      Significant difference with P value <.05.
       Neonatal intensive care unit admission2,157 (27.9)21,680 (19.9)0.9(0.8–1.0)
       Newborn antibiotics645 (8.4)6,224 (5.7)1(0.8–1.1)
       Immediate assisted ventilation1,082 (14)11,517 (10.6)0.75(0.7–0.8)
      Significant difference with P value <.05.
       Prolonged ventilation > 6 h525 (6.8)5,538 (5.1)0.7(0.6–0.8)
      Significant difference with P value <.05.
       Congenital malformation25 (0.32)449 (0.41)0.8(0.5–1.5)
       Chromosomal disorders8 (0.1)58 (0.05)2.2(0.6–7.8)
      Data are presented as number (percentage) unless otherwise indicated.
      Bar-El. Black women have fewer maternal and neonatal complications in pregnancies conceived via in vitro fertilization. Am J Obstet Gynecol 2022.
      a Significant difference with P value <.05.

      Conclusion

      On the basis of this large-scale, nationwide US study, maternal and neonatal complications that are generally seen more frequently in Black women are, in fact, lower in Black than in White women in the unique IVF population. Previous studies suggested that biological variations are the primary source of this disparity,
      • Slattery M.M.
      • Morrison J.J.
      Preterm delivery.
      and others described a multifactorial etiology, including limited access to education and healthcare and psychosocial stress, contributing to a long-lasting allostatic load.
      • Hamilton J.L.
      • Shumbusho D.
      • Cooper D.
      • et al.
      Race matters: maternal morbidity in the Military Health System.
      By analyzing the outcomes in IVF pregnancies where patients have an overall higher socioeconomic status and better access to medical care, and by further adjusting for socioeconomic factors, education, smoking, and prepregnancy medical conditions, we found that the Black race was no longer associated with the higher risk described in the general US population. The dramatic change in the racial disparity of these complications in the IVF population suggests that the adverse outcomes described in Black women are not solely biological in nature and that the Black race may not be an independent risk factor. Instead, the causes are likely multifactorial, with an emphasis on social determinants of health and prepregnancy health conditions. Thus, given our findings in the IVF population, we believe that focusing on the social determinants of health and improved prepregnancy health conditions is key in eliminating the racial disparity noted in maternal and neonatal outcomes in the general US population.

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