Ethnic differences in postmaturity syndrome in newborns. Reflections on different durations of gestation

To describe the prevalence, by weeks of gestation, of post-maturity signs in newborns by ethnic origins.

Observational cohort study (2001-2018), of all consecutive singleton births delivered at Center Hospitalier Universitaire Hospitalier Sud Reunion's maternity (Reunion Island, French overseas department, Indian Ocean). The presence of clinical post-maturity signs was recorded by a week of gestation using Clifford's clinical post-maturity signs in newborns (desquamation, dry skin, wrinkling fingers and cracked skin).

Of the 67,463 singleton births during the period, 58,503 newborns were from Reunion island, 5756 were of European origin (mainland France), and 4061 newborns from the archipelago of Comoros (North of Madagascar). Mean duration of gestation was 276 days in Caucasian women, 272 days in Comorian mothers and 273 days in Reunionese (p < .001). Post-maturity is defined by WHO as gestation greater than 293 days (41 weeks + 6 days). At 41 weeks (287 days) 12.1% of Caucasian babies presented post-maturity signs and 22.4% meconium-stained liquid versus respectively, 22.8 and 27.1% in Reunionese and 44 and 39.8% in Comorians (p < .001).

Among African (Black) pregnancies, duration of gestation was approximately 7 days shorter than in Caucasian (White) pregnancies. In the Reunionese intermixed population and Comorians, the gestation was shorter by 3-4 days. Black newborns presented severe clinical post-maturity signs beginning around 40 weeks and 4-6 days, while it was 1 week later in white infants. Consequences of these differences, with respect to clinical outcomes, are discussed.