Paternal race is a risk factor for preterm birth.

OBJECTIVE: The purpose of this study was to test the hypothesis that paternal race influences the risk for preterm birth. STUDY DESIGN: We conducted a population-based cohort study to examine the association of paternal race with preterm birth using the Missouri Department of Health's birth registry from 1989-1997. Birth outcomes were analyzed in 4 categories: white mother/white father, white mother/black father, black mother/white father, and black mother/ black father. RESULTS: We evaluated 527,845 birth records. The risk of preterm birth at <35 weeks of gestation increased when either parent was black (white mother/black father: adjusted odds ratio, 1.28 [95% CI, 1.13, 1.46], black mother/white father: adjusted odds ratio, 2.10 [95% CI, 1.68, 2.62], and black mother/black father: adjusted odds ratio, 2.28 [95% CI, 2.18, 2.39]) and was even higher for extreme preterm birth (<28 weeks of gestation) in pregnancies with a nonwhite parent. CONCLUSION: Paternal black race is associated with an increased risk of preterm birth in white mothers, which suggests a paternal contribution to fetal genotype that ultimately influences the risk for preterm delivery.

Racial disparity in the frequency of recurrence of preterm birth.

OBJECTIVE: We examined the hypothesis that black race independent of other factors increases the risk for extreme preterm birth and its frequency of recurrence at a similar gestational age. STUDY DESIGN: We conducted a population-based cohort study using the Missouri Department of Health's maternally linked database of all births in Missouri between 1989 and 1997 for factors associated with recurrent preterm delivery. RESULTS: Recurrent black preterm births occurred at increased frequency (adjusted odds ratio 4.11 [95% confidence interval 3.78 to 4.4.47]) and earlier gestations (31 versus 33 weeks' median age) than white births. Black siblingships also had higher multiplicity of prematurity (odds ratio 2.14 [95% confidence interval 1.49 to 3.07] and 5.09 [95% confidence interval 1.26 to 20.51] for 3 and 4 preterm births). Additionally, 47% of women delivered recurrent preterm infants within 2 weeks of the gestational age of their initial preterm infant. CONCLUSION: Overrepresentation of preterm births in blacks occurs independently of maternal medical and socioeconomic factors. Furthermore, the grouping of timing for preterm birth in different pregnancies of the same mother implicates important genetic contributors to the timing of birth.