OBJECTIVE: The neonate conceived by intrauterine insemination and in vitro fertilization are thought to be at increased risk of low birth weight. Although an increased rate of premature delivery has been reported previously, influences of controlled ovarian stimulation or sperm quality may also affect the birth weight. Poor maternal nutrition during pregnancy may also affect. The aim of this study was to investigate the relationship between infertility treatment and birth weight independent of premature delivery and abnormal maternal nutrition during pregnancy. DESIGN: Case control study. MATERIALS AND METHODS: Sixty-six infertility treatment subjects (Inf group) and 430 natural pregnancy subjects (N group) were studied at the Nagai clinic from 2002 to 2003. Case control matching was performed by maternal age, gestational age at delivery (≥37w), parity, height, before pregnancy weight and weight gain during pregnancy. Inf group was further divided into two groups of 36 in vitro fertilization subjects (ART group) and 30 intrauterine insemination subjects (IUI group). Evaluation parameters were neonatal weight (Wt), height (Ht), head circumference (Hc), chest circumference (Cc) and placental weight (PWt). RESULTS: For the Inf group, Wt, Ht, Hc, Cc and PWt were 2950±342g, 48.5±1.8cm, 32.7±1.3cm, 31.1±1.5cm and 560±82g, respectively (Mean±SD). For the N group they were 3067±360g, 49.0±1.7cm, 33.1±1.2cm, 31.6±1.5cm and 577±103g respectively. There was a significant difference between the Inf and N group in Wt, Ht, Hc, and Cc (p< 0.05, unpaired T test). Furthermore, measurements for the ART group were 2994±311g, 48.9±1.6cm, 32.8±1.3cm, 31.3±1.3cm and 565±96g respectively. Measurements for the IUI group were 2903±371g, 48.1±2.0cm, 32.5±1.3cm, 30.9±1.8cm and 556±66g, respectively. There were significant differences between ART, IUI and N group in Wt, Ht, Hc, and Cc (p< 0.05, one-way ANOVA). CONCLUSIONS: In this case control study, which eliminated the influence of premature delivery and abnormal maternal nutrition during pregnancy, there was a significant difference in average birth weight between the Inf and N group. Reasons for these differences may be a result of genetic phenotypes more common in parents who require infertility treatment or to preprogramming of the conceptus occurring as a result of the infertility treatment process. In addition, couples' nutritional state and lifestyle may also be considered. Prospective studies which control for these factors are needed for further investigation of this phenomenon.
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