For some perspective, births to women over 50 amounted to 0.02% of total births in 2013. There were more than ten times as many births among women 45-49 than women 50-54.
The age group with the most births was women age 25-29, with 1,120,777 births. For women past age 35, the number of births drops quickly. Births to women age 35-39 were less than half those for women age 30-34.
Though the majority of births are still to women under 35, birth rates for older women have increased in the past 20 years.
Congrats to the Cook family and their new additions!