Persistent discordant twin growth following IVF-ET.

We observed persistent first trimester growth disparity in a twin pregnancy following IVF-ET. The crown-rump length of the two fetuses was substantially different at 7 and 11 weeks and from the 20th week discordant growth was observed by intertwin differences in abdominal circumferences and estimated fetal weights. Birth weight discordance was 26.6% (1600/2180). This is apparently the first documentation of first trimester growth discordance persisting throughout pregnancy.