The preferred timing of second-trimester obstetric sonography based on maternal body mass index.
OBJECTIVE
To determine the preferred timing of sonographic screening of fetal anatomy based on the maternal body mass index (BMI).


METHODS
We abstracted the sonographic reports of 2,303 gravidas undergoing routine fetal anatomic screening between 15 and 24 weeks' gestation to determine the completeness of the study. Height and weight information was available on 1444 patients. The maternal BMI (weight [kilograms]/height [square meters]) was categorized as underweight (<19.8), normal weight (19.8-26.0), overweight (26.1-29.0), and obese (>29.0). Completion rates were compared by chi(2) analysis. Multiple logistic regression was used to evaluate for independent predictors of a completed study.


RESULTS
Except for underweight women, completion rates for all BMI categories were significantly higher when the sonographic examinations were performed between 18 weeks and 19 weeks 6 days compared with those performed between 15 weeks and 17 weeks 6 days. Body mass index, estimated gestational age, and black race were independent predictors of a completed study.


CONCLUSIONS
Except in underweight women, the 18- to 20-week interval appears to be superior to the 15- to 18-week interval when performing sonographic screening of the fetal anatomy.
Division of Maternal-Fetal Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. mlantz@jhmi.edu
Michael E
ME
Lantz
Christian A
CA
Chisholm
D000328:Adult; D015992:Body Mass Index; D005260:Female; D005865:Gestational Age; D006801:Humans; D016015:Logistic Models; D015588:Observer Variation; D011247:Pregnancy; D011262:Pregnancy Trimester, Second; D015203:Reproducibility of Results; D013997:Time Factors; D016216:Ultrasonography, Prenatal / Q000379:methods*