Statistical Analysis of Birth Weight and Gender of Newborn Infants

Introduction: Birth weight is an important determinant of infant morbidity and mortality. Its effect extends upto adult life and may explain some non-communicable diseases that may occur in adult life. In general, males weigh more than females. Birth weight is categorised into three levels, viz., low, normal and high. This study analysed the relationship between gender and the categories of birth weights.

Materials and Methods: Data on babies’ gender and birth weights from 961 term life deliveries in a private general practice hospital were analysed. Test on equality of the mean weight of males and females at the three categorical levels were done using z test and t-tests, as necessary.

Results: Mean birth weight was found to be 3.30 ± 0.495 kg. Males weighed significantly heavier than females at mean weights of 3.343 ± 0.495 kg and 3.258 ± 0.490 kg, respectively. In the low birth weight category, males weighed 1.844 ± 0.297 kg and females weighed 1.992 ± 0.397 kg. There was no significant difference. Similarly, the mean weight of males and females in the high birth weight category were 4.462 ± 0.343 kg and 4.342 ± 0.219 kg, respectively with no significant difference. In the normal weight category, males weighed significantly more than the females with the mean weight of 3.30 ± 0.359 kg and 3.248 ± 0.392 kg, respectively.

Conclusion: Male babies weighed more than female babies only in the normal birth weight category. The factor that selectively affected the birth weight of male babies must be acting under the category of normal birth weight only.

More studies are necessary to identify the factors and the reasons, for which they act only at the level of the normal birth weight.