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Genetic influence on parturition in a twin sample: Examination of parental effect on birth timing

      Objective

      Prior twin studies suggest that maternal hereditary factors contribute to preterm birth, but the magnitude of paternal genetic influences is unknown. This study was undertaken to test the hypothesis that paternal, as well maternal, genetics contribute to birth timing.

      Study design

      A database including >19,000 births to monozygotic (MZ) twins, dizygotic (DZ) twins, siblings and parents of twins was created from Dutch twin surveys. Quantitative genetic methods were utilized to examine correlation coefficients(r) and concordance of birth timing (# weeks of variation) in the offspring of twin pairs. The variation in birth timing was calculated by comparing the gestational age of the 1st birth of twin 1 to any birth of twin 2.

      Results

      This study included 273 twin pairs (43 male, 230 female) + 27 male siblings of DZ male pairs. There were 1269 births to these parents. We found a higher correlation of birth timing in MZ than DZ twin mothers (rMZ = 0.31, rDZ = 0.15). This trend was not present for twin fathers (rMZ = 0.08, rDZ = 0.22). The # weeks of variation in birth timing between twin pairs indicate close concordance for both MZ and DZ female pairs compared to male pairs (see table).

      Conclusion

      Tabled 1Birth Timing Correlation
      Twin PairTwin# BirthsCorr.Coef. (p)Wks of Variation (SD)
      MZ Male (34)178−0.08 (0.32)0.34 (±3.42)
      267
      MZ Female (158)13360.31 (0.00)0.09 (±2.35)
      2339
      DZ Male (9) + male sibs (27)1780.22 (0.09)0.13 (±3.79)
      275
      DZ Female (72)11660.15 (0.11)−0.03 (±2.90)
      2130