Comparison of fetal growth in singleton, twin, and triplet pregnancies

The objective of this longitudinal retrospective study was to evaluate diff erences of the fetal growth and fetal organ growth among singleton small fo r gestational age (S-SGA), singleton appropriate for gestational age (S-AGA ), twin (Tw-AG), and triplet (Tri-AGA) infants, Ultrasonographic examinatio ns were performed on 35 S-AGA, 18 S-SGA, 52 Tw-AGA and 12 Tri-AGA fetuses. Circumferences of head (HC), abdomen (AC), spleen (SC) and adrenal gland (A GC) and lengths of femur diaphysis (FDL), liver (LL), estimated weight (EWT ) were measured every 2 weeks after 15 weeks of menstrual age until deliver y. There was no significant difference in predicted HC values in S-AGA, Tw- AGA and Tri-AGA fetuses; these values were lowest in S-SGA fetuses. As the number of fetuses in the uterus increased with advancing menstrual age, the slope of the growth curve for predicted AC value became lower, but there w as no significant difference between Tri-AGA and S-SGA fetuses. There was n o significant difference in predicted PDL values among Tw-AGA,Tri-AGA and S -SGA fetuses; those values were significantly lower than that in S-AGA fetu ses. There was no significant difference in predicted EWT value between Tw- AGA and Tri-AGA fetuses, which were intermediate between those for S-AGA an d S-SGA fetuses. There were no significant differences in predicted SC and AGC values between S-AGA and Tw-AGA; fetuses, respectively. However, in S-S GA fetuses, the slopes of the growth curve for SC and AGC were lower than t hose in the other two groups with advancing menstrual age. There were sligh t differences in predicted LL values between S-AGA, S-SGA and Tw-AGA fetuse s, These results suggest that in AGA fetuses, there was a slight difference in growth pattern among singleton, twin, and triplet pregnancies.