Race and ethnicity are among the predisposing factors for fetal malpresentation at term

Fetal malpresentation complicates approximately 3% to 4% of all term births. It requires special considerations for delivery and exposes the mother and neonate to obstetrical interventions and potential adverse outcomes, such as umbilical cord prolapse, head entrapment and birth trauma, hypoxic ischemic encephalopathy, cesarean delivery, and cesarean delivery-related complications. We set out to explore the maternal and fetal factors associated with noncephalic malpresentation at term, with specific interest on the impact of maternal race and ethnicity on fetal malpresentation.

This was a retrospective analysis of the Centers for Disease Control and Prevention Natality Live Birth database for the years from 2016 through 2018. All term, singleton deliveries for the following racial and ethnic groups were included: non-Hispanic White, non-Hispanic Black, Asian, and Hispanic. Race and ethnicity were assigned based on self-identification and individuals with >1 racial category were excluded from the analysis. Malpresentation was defined as a noncephalic presentation at term and included breech and transverse presentations. The malpresentation group included all noncephalic births and cephalic births that occurred following successful external cephalic version, whereas all other cephalic births served as controls. A multivariable logistic regression analysis was used to assess the rate of malpresentation, with adjustment for potential confounders including maternal age, race and ethnicity, parity, birthweight, fetal malformations, malformations of the central nervous system (CNS), and chromosomal anomalies. The results are displayed as adjusted odds ratios (aORs) with 95% confidence intervals (CIs). Statistical significance was set at a P value of <.05. Institutional review board approval was not required because the de-identified data are publicly available through a data use agreement.

There were 9,692,203 term, singleton births during the study period. The malpresentation group included 354,689 births (3.66% of the total). The Table shows the rate of malpresentation for various maternal and fetal factors. We found a substantial racial and ethnic disparity in the malpresentation rates. Non-Hispanic White women had the highest malpresentation risk, whereas non-Hispanic Black women had the lowest risk (3.93% vs 2.81%; aOR, 1.38; 95% CI, 1.36-1.39). Hispanic and Asian women were also at increased risk for malpresentation when compared with non-Hispanic Black women (aOR, 1.30; 95% CI, 1.29-1.32 and aOR, 1.12; 95% CI, 1.10-1.14, respectively). In addition, several maternal and fetal conditions were noted to be associated with an increased risk for malpresentation at term, including older maternal age (aOR, 2.81; 95% CI, 2.74-2.88; for patients >40 years), nulliparity (aOR, 1.50; 95% CI, 1.48-1.51), low birthweight (aOR, 1.80; 95% CI, 1.77-1.83 for birthweight under 2500 g), and fetal malformations of the CNS and chromosomal anomalies (aOR, 3.53; 95% CI, 3.06-4.06 and aOR, 2.32; 95% CI, 2.05-2.63, respectively).

Based on a large US population database, we identified several maternal, fetal, and racial and ethnic factors that are associated with an increased rate of noncephalic malpresentation at term. Specifically, fetal CNS malformations, congenital or chromosomal anomalies, advanced maternal age, low birthweight, and nulliparity are risk factors for noncephalic presentation. Interestingly, non-Hispanic White women have the highest risk for malpresentation, whereas non-Hispanic Black women have the lowest risk. Previous publications found that low birthweight, advanced maternal age, nulliparity, and congenital fetal malformations are risk factors for malpresentation.^1-3 Nonetheless, the current data available on race and ethnicity are sporadic, with limited reports suggesting that sub-Saharan ethnicity is associated with a lower rate of malpresentation² and that White race is associated with a higher rate.⁴ We present a large-scale, nationwide US-based study to confirm the racial and ethnic disparity regarding malpresentation in the United States. This may be explained by the known variation in the shape of the bony birth canal in different racial and ethnic groups and populations from different geographic locations.⁵ Further investigation is needed to explore the racial and ethnic disparity described.