OBJECTIVE: Studies have demonstrated that infants of assisted reproductive technologies (ART) are at increased risk for adverse outcomes, such as low birth weight, compared with naturally conceived pregnancies. It is unclear, at what gestational age these changes are initiated, and whether these risks are a result of infertility or the fertility treatment. Thus, the objectives of our study were: 1) to compare first trimester fetal biometry, as an early marker of fetal growth, in patients conceiving either spontaneously or through infertility treatment; and 2) to compare early fetal biometry in pregnancies resulting from in-vitro fertilization (IVF) to those from other fertility treatments (in-vivo fertilization).DESIGN: Retrospective case-control study.MATERIALS AND METHODS: Analysis was conducted on all singleton pregnancies who presented to our institution for chorionic villus sampling (CVS) from 7/2000 to 4/2004. Ultrasounds were performed at the time of CVS between 9 and 12 weeks. Women were classified as either receiving infertility treatments or conceiving spontaneously. Infertility patients were further divided into those achieving pregnancy through IVF or through other fertility treatments. The mean gestational age (by LMP, date of IUI, or date of oocyte aspiration) and mean crown rump length (CRL) was calculated for each group. Data was analyzed using the T-test to compare means, or Fisher's exact test.RESULTS: 1,535 patients who spontaneously conceived, and 135 patients who conceived through ART, were included in the analysis. In the fertile and infertile patients, mean CRL was 51.6 and 50.8 mm, respectively. When we compared the patients who conceived through IVF (n = 64) to those who conceived through in-vivo treatments (n = 63), mean CRL for each group was 51.6 and 50.8 mm, respectively. These results were not significantly different. In the fertile and infertile groups, mean maternal age was 39.0 and 39.7. This difference was small, though statistically significant. No significant differences were found in other parameters when comparing groups.CONCLUSIONS: Pregnancies conceived by infertile couples are not smaller in the late first trimester when compared to spontaneously conceived pregnancies. In addition, there is no difference in the size of pregnancies conceived through ART compared to those from in-vivo treatments. Although ART pregnancies have been associated with low birth weight, this does not appear to be a phenomenon that occurs early in gestation. OBJECTIVE: Studies have demonstrated that infants of assisted reproductive technologies (ART) are at increased risk for adverse outcomes, such as low birth weight, compared with naturally conceived pregnancies. It is unclear, at what gestational age these changes are initiated, and whether these risks are a result of infertility or the fertility treatment. Thus, the objectives of our study were: 1) to compare first trimester fetal biometry, as an early marker of fetal growth, in patients conceiving either spontaneously or through infertility treatment; and 2) to compare early fetal biometry in pregnancies resulting from in-vitro fertilization (IVF) to those from other fertility treatments (in-vivo fertilization). DESIGN: Retrospective case-control study. MATERIALS AND METHODS: Analysis was conducted on all singleton pregnancies who presented to our institution for chorionic villus sampling (CVS) from 7/2000 to 4/2004. Ultrasounds were performed at the time of CVS between 9 and 12 weeks. Women were classified as either receiving infertility treatments or conceiving spontaneously. Infertility patients were further divided into those achieving pregnancy through IVF or through other fertility treatments. The mean gestational age (by LMP, date of IUI, or date of oocyte aspiration) and mean crown rump length (CRL) was calculated for each group. Data was analyzed using the T-test to compare means, or Fisher's exact test. RESULTS: 1,535 patients who spontaneously conceived, and 135 patients who conceived through ART, were included in the analysis. In the fertile and infertile patients, mean CRL was 51.6 and 50.8 mm, respectively. When we compared the patients who conceived through IVF (n = 64) to those who conceived through in-vivo treatments (n = 63), mean CRL for each group was 51.6 and 50.8 mm, respectively. These results were not significantly different. In the fertile and infertile groups, mean maternal age was 39.0 and 39.7. This difference was small, though statistically significant. No significant differences were found in other parameters when comparing groups. CONCLUSIONS: Pregnancies conceived by infertile couples are not smaller in the late first trimester when compared to spontaneously conceived pregnancies. In addition, there is no difference in the size of pregnancies conceived through ART compared to those from in-vivo treatments. Although ART pregnancies have been associated with low birth weight, this does not appear to be a phenomenon that occurs early in gestation.