New Treatments for Genital Warts Less Than Ideal

To the Editor.— Maternal smoking during pregnancy often results in smaller than normal neonates.¹ The mechanisms by which maternal smoking impairs fetal growth are as yet undefined. Insulinlike growth factor I (IGF-I) is an essential regulator of fetal growth² and may be a target for the growth-retarding effects of smoking.

We measured concentrations of IGF-I and its major binding protein (IGF-BP3) in cord serum of 10 smoking and 9 nonsmoking mothers (median age, 27 years and 28 years, respectively) who, after an otherwise entirely uneventful pregnancy, gave birth to normal-term neonates. The smoking group by history had had at least 15 cigarettes daily for longer than the last 2 months of gestation. The nonsmoking control group was neither actively nor passively exposed to cigarette smoke. For assessment of nicotine exposure, we also determined concentrations of the nicotine metabolite cotinine in maternal hair obtained at delivery. Hair samples of 50 mg were digested overnight at 50°C with 0.6N sodium hydroxide. The cotinine content of the extract was measured by enzyme-linked immunosorbent assay.³ The detection limit of the cotinine assay was 0.1 ng/mg of hair and the interassay coefficients of variation were less than 9%. Concentrations of IGF-I and IGF-BP3 in umbilical cord serum (after separation from each other by acid extraction) were determined by specific radioimmunoassays,^4- 5 and the coefficients of interassay variation of both assays were less than 7%.