THE SEX-RATIOS OF FAMILIES WITH A NEURODEVELOPMENTALLY DISORDERED CHILD

It has been conjectured that mothers who give birth to neurodevelopmen tally disordered (ND) children may have hormonal or immunological char acteristics that bias them toward giving birth to male children. We ex amined this hypothesis in an epidemiological sample of 2,080 ND childr en drawn for the National Collaborative Perinatal Project (NCPP) who h ad one of nine kinds of NDs. No assumptions were made regarding the se x ratio of non-ND children since this could be computed from NCPP data for 11,213 families. The sex ratio of families with ND children was n ot significantly biased toward boys as compared to the sex ratio of fa milies with non-ND children, provided that the index ND child was excl uded from the analysis.