There were more babies born in the United States in 2007 than were born in the busiest year of the World War II baby boom, leaving statisticians wondering if 2007 might be the beginning of a new baby boom. When examined more closely, those 2007 births represent some ups and some downs in recent trends.

The 4.3 million babies born of all mothers in 2007 is more than even in 1957, the year that produced the most babies in the post-war baby boom. Unfortunately, 2007 marked the second consecutive year in an increase of babies born to teenage mothers, following a 14-year decline in this age group.

The number of teenage mothers grew 5% between 2005 and 2007, according to the latest report from the Centers for Disease Control and Prevention’s (CDC’s) National Center for Health Statistics. The number of babies born to girls between 15 and 19 years of age rose 1% from 2006 to 2007, to 42.5 births per 1,000 girls of that age group. This increase in teen births comes after a 14-year period of decline.

Good news is that the number of children born prematurely and of low birth weight dropped in 2007 after a prolonged increase in both categories. Between the 1980s and 2007, the premature birth rate rose by as much as one-third but dropped 1% between 2006 and 2007. The number of babies of low birth weight dropped for the first time since 1984.

According to the March of Dimes, premature births, occurring before the 37th week of pregnancy, are the leading cause of death to infants in the US. These pre-term births are said to cost as much as $26 billion each year. Low birth weight also increases a child’s risk of medical and developmental problems.

2007 also marks the 11th consecutive year that the number of cesarean deliveries has risen, going up 2% from 2006, for a total of 31.8% of all births that year. The advocacy group, International Cesarean Awareness Network, describes this trend as a cause for alarm, saying at least half of all cesarean deliveries are unnecessary and any major surgery, including a cesarean delivery, takes its toll on women who are otherwise healthy and their babies, too.

Additional data from the CDC report says 39.7% of the 2007 baby boom was unmarried mothers. Of Hispanic babies born in 2007, 51.3% were to unmarried women as were 71.6% of the black babies.