The number of babies born in the United States reached a historic high in 2007, and new estimates for that year show that unmarried women in their 30s account for a large part of the baby boost.

The 2007 total of more than 4,317,000 births surpasses the peak of the post-war baby boom in 1957, says a new government report. Births to Asian and Pacific Island women and among American Indian teenagers showed the greatest increases.

Birth rates for most age groups were up about 1 per cent over 2006. The teenage birth rate rose by 1 per cent in 2007 after a 4 per cent increase from 2005 to 2006 -- rises that have interrupted a 34 per cent decline in teen births from a peak in 1991 to 2005.

But birth rates for women aged 25 to 29, and 30 to 34 increased by 2 per cent -- double the average increase. For women in their early 30s the general fertility rate was almost 100 births per 1000, the highest since 1964 (when it was 103.4) at the end of the US baby boom. The rate for women in their late 30s continued its nearly three decade rise, and births to women aged 45 to 54 were up 5 per cent.

It was unmarried women, however, who did most to push the figures up, bringing their share of all births to nearly 40 per cent (39.7). Their birth rate rose 5 per cent in 2007, and births to the unmarried in each age group 15 years and over “far outpaced” the increase in total births for women aged 15 to 39 years, says the report. The 2007 total is up 26 per cent from 2002, when the recent steep increases began. The largest increases in non-marital births were to women aged 25 to 39 years -- up 6 per cent or more over 2006. While the great majority of births to teenagers are non-marital, 60 per cent of births to women aged 20 to 24, and almost one-third of births to women aged 25 to 29 were also non-marital.

In terms of population, the US has strengthened its position, since its total fertility rate (TFR)* is over 2.1 -- replacement level -- for the second year in a row. However, increases in single and cohabiting parenthood raise concerns about the future of the family. ~ Centers for Disease Control, National Vital Statistics Reports, Vol 57, No 12, Births: Preliminary Data for 2007; March 18, 2009

*TFR summarises the potential impact of current fertility patterns on completed family size by estimating the average number of births that a hypothetical group of women would have over their lifetimes, based on age-specific rates in a given year.

Cross-posted from Family Edge, another MercatorNet blog.