EP05.10: Is there a link between maternal PAPP‐A values and SGA?

Abstract

To identify the incidence of SGA fetus where PAPP-A values were <0.4MoM as a part of Down's syndrome screening During the study period from 01/04/2009 until 25/04/2013 (4 years), there were 23925 antenatal bookings and 20376 deliveries. A total of 16042 first trimester Down's syndrome screening tests were performed, off which 850 women were identified with PAPP-A values <0.4MoM. The tests involved nuchal translucency measurements followed by serum biochemistry for free beta human chorionic gonadotrophin, (free beta hCG) and Pregnancy associated plasma protein A (PAPP-A) levels. The Down's syndrome risk at term was then generated. The PAPP-A values ranged from 0.03 to 0.4 MoM. The Down's syndrome risk ranged from 1:2–1:50,000. Prenatal testing were offered to all high risk women to exclude chromosomal aneuploidy. Various outcomes such as gestational age, onset of labour, mode of delivery, birthweight and neonatal admissions were analysed. Out of total 850 cases, 121 were excluded due to lack of available details, termination of pregnancies and miscarriages. Out of remaining 729 cases, 640 fetuses were born >/=37 weeks gestation and 89 were < 37 weeks gestation. Of these 640 fetuses, 603 (94.2%) weighed > 2.5 kg (>5th centile) and 37 cases (5.8%) were < 2.5 kg. There was also 1 still birth in the cohort of women >/=37 weeks. Our retrospective study demonstrated 5.8% incidence of SGA fetuses when only a single factor, PAPP-A <0.4 MoM was considered. This study, however did not take into account any other factors such as mother's socio-economic history, past obstetric history or any underlying medical conditions that may contribute to SGA fetus. In clinical practice, it is important to identify these high risk cases, but prior to offering appropriate antenatal surveillance, there is a need for developing a standardised risk based tool so that it can be practiced in all types of health care settings. Further research is also needed to unlock the link between low PAPPA and defective placentation in pregnancies unaffected with aneuploidy or genetic abnormality.