Random facts about birth in the United States

When and where babies arrive

Super Tuesday: The most popular day for babies to make their entrances? It's still Tuesday, which boasted more than 13,000 births on average in 2003. That's about 16 percent more babies than on any other day of the week. Saturday is the slowest day, with an average of about 7,500 births (in part because doctors don't schedule c-sections and inductions on weekends).

Some (babies) like it hot: More newborns arrive in the late summer/early fall months of July, August, and September than any other time of the year.

Go West: As of 2003, the states with the highest birth rates are mostly west of the Mississippi: Alaska, Arizona, California, Colorado, Idaho, Nevada, Texas, and Utah — with Georgia being the lone high-birth-rate state on the other side of the divide.

All about moms

The waiting game: Over the last three decades, women have been waiting longer to become moms. In 1970, the average age for a first-time mother was about 21 — today, she's more likely to be 25 to 29 years old.

Weighing in: Moms-to-be in the United States gain a median of about 30 pounds during pregnancy (that means half gain more, half gain less). This number has stayed constant since 1990.

Birth and delivery

Doctor, doctor: The vast majority of moms in the United States give birth in hospitals (99 percent) with the help of a physician (91 percent). But women are increasingly choosing other providers — today, midwives attend about 8 percent of births, up from less than 1 percent in the mid-'70s.

C-sections soaring: The number of cesarean deliveries has skyrocketed by more than 40 percent in the last decade to 29 percent of births, the highest rate ever reported in the United States.

Giving labor a push: The number of women whose labor is induced has more than doubled since 1990, to about 10 percent of births.

Boy power: Boy babies outnumber girl babies, with about 1,049 males for every 1,000 females — a ratio that's stayed about the same over the past 60 years.

Early birds: More babies are being born prematurely, partly because of the rise in twin births and in scheduled cesareans and inductions. The preterm delivery rate has gone up more than 30 percent since 1981. In 2004, about 12.5 percent of births were early arrivals (most moderately early, from 32 to 36 weeks).

Little lightweights: The number of low-birthweight babies (less than 5 1/2 lbs.) has been on the rise, which researchers say is due in part to more older moms, more twins being born, and the growing use of fertility treatments. About 8.1 percent of babies born in 2004 were low birthweight — the most reported since 1970, and a more than 16 percent climb since 1990.