Abstract
BackgroundAsymmetric fetal growth and male sex are both associated with adverse neonatal outcome. However, less is known about the influence of asymmetric growth and fetal sex within SGA neonates, a group of infants already at increased risk for adverse neonatal outcomes. The aim of the present study was to provide insight into variance in risk factors for SGA in a fetal sex- and growth symmetry-specific way.MethodsFor this prospective, multicenter cohort study, data from the Screening for Pregnancy Endpoints (SCOPE) study were used with 5628 nulliparous participants, of which 633 (11.3%) pregnancies were complicated with SGA and 3376 (60.0%) women had uncomplicated pregnancies. Association between risk factors for SGA, SGA subgroups, and uncomplicated pregnancies were assessed with multivariable analyses.ResultsPrevalence of asymmetric growth varied from 45.8% of SGA infants to 5.5% of infants with a customized birthweight > 90th percentile (p < 0.001). Significantly more SGA males had asymmetric growth compared to SGA female infants (51.2% vs 40.4%, p = 0.009). Maternal pre-pregnancy diet and BMI < 20 and ≥ 30 were significantly associated with symmetric SGA but not with asymmetric SGA. Asymmetric SGA infants had not only lower customized birthweight percentile (4.4 (SD 2.8) vs 5.0 (SD 3.0), p < 0.001), but also lower rates of stillbirth (p = 0.041) and less often Apgar scores < 7 (p = 0.060).ConclusionsAmong SGA infants, low customized birthweight percentiles and male sex are associated with asymmetric growth. Only symmetric SGA is significantly associated with maternal risk factors in early pregnancy. There is a substantial variance in risk factors and neonatal outcomes for SGA based on growth symmetry, implying a different pathogenesis.Trial registrationACTRN12607000551493
Highlights
Asymmetric fetal growth and male sex are both associated with adverse neonatal outcome
A total of 5690 participants were enrolled in the Screening for Pregnancy Endpoints (SCOPE) study of whom 62 (1.1%) participants were lost to follow-up or had a miscarriage or termination before 20 weeks’ gestation
Main findings The data from this large prospective cohort demonstrate that there is a substantial variance in risk factors and neonatal outcome for Small for gestational age (SGA) based on fetal sex and growth symmetry
Summary
Asymmetric fetal growth and male sex are both associated with adverse neonatal outcome. Less is known about the influence of asymmetric growth and fetal sex within SGA neonates, a group of infants already at increased risk for adverse neonatal outcomes. Detection of FGR may benefit from closer monitoring and early intervention, methods of monitoring FGR are improving, current methods are not yet reliable [14] Both FGR and SGA are associated with increased rates of stillbirth and adverse perinatal outcome, not all FGR will result in a SGA infant as the birth weight may be restricted but not below the designated customized birthweight percentile [3, 14, 15]. Previous studies have shown that asymmetric infants are at increased risk for neonatal death, operative interventions and respiratory distress compared to symmetric infants [4, 15, 17,18,19,20]
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