New Census data indicate that two processes around the preference for a male child are going on simultaneously in India — prenatal sex determination and repeated pregnancies. Data on family sizes and sex ratios released on Monday showed that at every family size, there were more boys born than girls. However as family sizes got bigger, the sex ratio within the family got much less skewed, indicating that families with fewer or no sons were the ones choosing to have repeated pregnancies.

Among women who had ever had one child, 22 million said that they had had a girl and 28.5 million had had a boy, clearly indicating a disproportionately large number of boys being born. Among women who had given birth to two children, 26 million had two boys while just half that number -- 13.3 million -- had two girls.

This was similarly the case among families with three children -- families with all three boys or two boys and a girl were far more common than families with all three girls or two girls and a boy.

However at higher family sizes, this dynamic begins to change, as families that cannot or do not practise prenatal sex selection have repeated pregnancies in their quest for a son, a senior Census official explained. Families with six children, for instance, are far more likely to have all six girls than all six boys, the data shows; there were 0.9 million such families, as against just 0.3 families with all six boys.

As families get larger, the survival odds of girl children also begin to falter, the data shows. Among families where the woman had given birth to one child, the odds of the girl child surviving were slightly higher than the odds of the boy surviving, partly explained by the lower natural infant mortality of girls. Among families with two children, survival odds for girls worsened but were still comparable. However among families with six children, the odds of the survival of daughters fell sharply.