AUGUSTA – The annual percentage of babies born to unwed mothers has nearly doubled in Maine over 15 years, according to U.S. Census figures.

But overall, the number of births in the state has remained relatively constant, say the figures for 1998, the most recent year for which numbers are available.

The Census figures indicate 4,100 babies – or 30 percent of all births – were born to unmarried mothers in 1998, about the same percentage as during the previous year but nearly double that of 1984.

A state Department of Human Services official said social morals have changed over the years, so women today can choose to have babies without being married.

“The [1998] statistics don’t differentiate whether it was a chosen birth or if it was unchosen, or whether the woman was living with a partner,” said Barbara Van Burgel of the DHS Bureau of Family Independence.

A scientific survey conducted by the state indicates that two-thirds of all pregnancies in 1998 were intended, but the number drops to 21 percent among 15- to 17-year-olds, said Nancy Birkhimer of the DHS Division of Community and Family Health.

Census figures also show that for the first time since 1989, the number of births in the state has increased, but the figure is so small it’s not considered significant.

In 1998, 13,720 babies were born in Maine, an increase of 63 from the previous year. The state’s population is about 1.25 million.

Health advocates were concerned over other figures showing that 20 percent of women who gave birth in 1998 smoked an average of 13 cigarettes a day during their pregnancies.

The percentage has remained steady for several years and is lower than it was 10 years ago, when 30 percent of women were smoking during pregnancy, said Sarah Haggerty, director of the Partnership for a Tobacco-Free Maine.

Smoking while pregnant increases risks of low birth weight babies and health problems.