Aetiology and short-term outcome in periviable fetal growth restriction associated with structural and chromosomal abnormalities.

Objective To investigate the aetiology and the short-term outcome of fetuses diagnosed with severe periviable fetal growth restriction (FGR) associated with structural defects, and chromosomal or genetic abnormalities. Design Retrospective database study (2005–2018) at a single Fetal Medicine unit. Methods We included viable singleton pregnancies in which FGR was defined by abdominal circumference <3rd percentile diagnosed at 22+0–25+6 weeks and associated with structural defects, and chromosomal or genetic abnormalities. Results Fifty-five cases were included at median gestational age 23+4 (22+0–25+6) weeks. Genetic testing was performed in 39 and yielded an abnormal result in 17 (44%), represented by trisomy 18 (9) and one each for trisomy 21,13, triploidy, trisomy 22 mosaicism, osteogenesis imperfecta, Russell–Silver, Wolf–Hirschhorn, and one undefined abnormality. In 2 fetuses, a skeletal dysplasia phenotype was clinically suspected and multiple structural defects in the context of consanguinity in 4. Major structural abnormalities associated were found in 31 (56%) represented by CNS (9), gastrointestinal (8), and major cardiac defects (3). Perinatal outcomes were available for 51/55; of 51, 20 (39%) women opted for termination, 21 fetuses (41%) died in utero or neonatally leaving 10 (20%) surviving beyond the neonatal period. Conclusions Little is known about FGR babies that are also abnormal, as opposed to those having uteroplacental insufficiency. Almost half are associated with a genetic condition, and the other half have a major structural defect. This condition is associated with a high mortality rate in utero and postnatally with a lower than 1 in 5 chance of survival beyond the neonatal period.