試管嬰兒較小？

試管嬰兒較小？

Research suggests that IVF pregnancies result in smaller neonates and more adverse perinatal outcomes, but compare IVF pregnancies to the general fertile population. The etiology of the underlying infertility is an important consideration. Our objective was to determine whether fetal size differences exist between pregnancies conceived spontaneously and those from assisted reproduction in an infertility cohort.

DESIGN: Retrospective Cohort.

MATERIALS AND METHODS: Patients with an infertility diagnosis, a singleton live birth (1/1/99-2/1/09) and close follow up within our hospital system were selected. Extremely well dated spontaneous conceptions, ovulation induction (OI) and fresh, non-oocyte donor IVF pregnancies were included. Comparisons were made between crown rump length (CRL) at 6 wk US, femur length (FL) and estimated fetal weight (EFW) at mid-gestation and birthweight. Multivariate analyses were performed to adjust for biologic or statistically significant factors in fetal size.

RESULTS: Of 2350 patients screened, 473 fit strict inclusion criteria. Controlling for confounding variables (fetal/maternal age, gender, pregnancy outcomes, maternal health), there was no difference in CRL, FL, EFW or birthweight between the prevalent types of infertility (Unexplained n=116, male factor n=129, ovulation d/o n=142, tubal factor n=78). IVF pregnancies were larger early in gestation (CRL 8.3+4.3mm) vs. spontaneous (6.4+4.6; p=0.024) & OI (6.4+3.9; p=0.002), smaller at mid-gestation (FL 2.9+0.6cm) vs. spontaneous (3.2+0.4; p=0.005), but equal to OI (3.1+0.5; p=0.11). At delivery, OI infants were smaller than IVF or spontaneous (3086+660gm vs. 3300+634, p=0.01& 3242 +668, p=0.001).

CONCLUSIONS: IVF singletons are not smaller when compared to those in a spontaneous infertility cohort. Yet, fertility treatments may affect fetal growth rates in utero and OI differences may persist postnatally. Further study is warranted to determine whether the growth alterations have clinical relevance in offspring later in life.

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