Labor in pregnancies with small for gestational age suspected fetuses

Fetal growth restriction (FGR) is an unclearly defined condition described as a fetal weight which is too low in relation to gestational age. It is recognized in 10-15% of singleton pregnancies and can lead to severe complications, including stillbirth. To reduce the adverse fetal and neonatal outcomes, many medical interventions are being introduced by obstetricians. These, like all medical procedures, may induce further complications, such as preterm labor and its consequences.

The aim of this study was to assess in terms of perinatal and neonatal outcomes such management procedures as expectant monitoring, induction or elective cesarean section (ECS) in pregnancies where the fetus is suspected of being small for gestational age (SGA). There was also the goal of determining the specificity of ultrasound examination in the recognition of SGA.

The single-center retrospective study was carried out among 146 patients who were prenatally suspected of having SGA pregnancies and who delivered in our hospital. Small for gestational age was defined as estimated fetal weight (EFW) in the 10th percentile or below. The output cohort was divided into 2 subgroups: group A - with antenatally confirmed hypotrophy, and group B - without antenatally confirmed hypotrophy.

Out of 146 newborns suspected of being SGA, 65 had a birth weight in the 10th percentile or below, and the estimated positive predictive value of ultrasound examination amounted to 44.5%. Underweight mothers correlated with 5 times higher rates of SGA overdiagnosis. Serious neonatal complications, such as neonatal deaths, respiratory or cardiovascular dysfunctions, and admission to the neonatal intensive care unit (NICU), occurred significantly more often in confirmed SGA cases (46% vs 19% in group B, with a p-value of 0.0066, 0.0253, 0.0027, and 0.0253, respectively). The highest rate of ECS concerned patients from group A (44.6% vs 30.9% in unconfirmed samples; p = 0.04), while expectant management was more often associated with neonatal death and admission to the NICU than with elective procedures (18.2% vs 7.4% and 36.4% vs 27.8%, respectively).

Customized charts used during ultrasound examination, which evaluate additional parameters such as body mass index (BMI), may decrease the overdiagnosis of SGA.