INCIDENCE AND EPIDEMIOLOGY — In the United States, maternal age specific birth rates for 2004 were: 15 to 17 years (22.1 per 1000 women), 18 to 19 years (70.0 per 1000), 20 to 24 years (101.8 per 1000), 25 to 29 years (115.5 per 1000), 30 to 34 years (95.5 per 1000), 35 to 39 years (45.4 per 1000), 40 to 44 years (9.0 per 1000), and 45 to 54 years (0.6 per 1000) [1].
In 2002, 263 births were reported in women from 50 to 54 years of age [2]. Women 50 years of age or older are more likely to conceive with the assistance of ART and to have a multiple gestation and to have a disproportionate number of low birth weight and very low birth weight babies [3]. Births to women as old as 66 years of age using ART have also been reported worldwide. The oldest woman to achieve a naturally conceived pregnancy was 57 years old.
The percentage of pregnancies in women greater than or equal to 35 years of age in the United States was about 14 percent before World War II, dropped to about 5 percent in the 1970s and, since the 1980s, rose to about 14 percent in 2002 [4]. The large number of births to this age group is expected to continue for another decade, when the youngest baby boomers will enter menopause. The increased occurrence of births at older maternal ages relates not only to the increased number of women aged 35 to 45, but also to later marriage, second marriage, the availability of better contraceptive options, and wider opportunities for further education and career advancement.
Source: http://patients.uptodate.com/print.asp?print=true&file=antenatl/14857
