Phenotypic clustering of families with recurrent preterm deliveries

OBJECTIVE: Familial predilection for preterm deliveries was previously
reported. However, there is lack of information whether this
tendency is attributed to a specific phenotype like spontaneous or
indicated Preterm delivery (PTD) or it is sporadic without specific
predilection. The aim of this study was to determine whether families
with preterm births in more than one generation has specific
phenotypic clustering of PTD
STUDY DESIGN: A retrospective population based study was conducted
including all families in which women delivered prematurely
in more than one generation. PTD phenotype was divided into three
groups, spontaneous, indicated, and mix. The enrichment of a
specific phenotype among the PTDs of each family was tested by
using binomial distribution function.
RESULTS: Our cohort included 3059 women who had 13375 preterm
deliveries. There were 293 families who had preterm deliveries in 2
or more generations. There were 8 (2.7%) families with indicated
PTD phenotype in which the number of indicated PTD was higher
than the expected probability in our cohort (p<0.05), and 285
families with a mixed phenotype. There was no family with a
spontaneous labor enriched phenotype. Among the families with
enriched indicated phenotype there was one family that had higher
number of PTDs complicated by preeclampsia than expected
(p¼0.049). In the group of mix PTD phenotype there were nine
families (3.1%) with higher number of PTD complicated by preeclampsia,
eight families (2.8%) with preterm PROM and four
families (1.4%) with SGA neonates and the etiology for their PTDs.
CONCLUSION: Families with PTDs in more than one generation have
mostly a mix phenotype of spontaneous and indicated preterm
births. We bring herein a preliminary report of specific familial
phenotype of indicated PTDs. In addition, even among families with
a mixed phenotype specific causes for preterm deliveries such as
preeclampsia or preterm PROM may be more prevalent.