More and more women are having babies outside of marriage in Hawaii and across the country, accounting for roughly 4 out of 10 births last year, but teenagers aren’t responsible for the trend.

The teen birthrate has dropped dramatically in recent years, while older women are giving birth without a marriage certificate at ever-increasing rates. Some unmarried moms are single but a growing number — more than half at last count — are living with their partners.

"We are pretty stable — we have been together for five years," said Ha‘aheo Sai, a 23-year-old medical assistant who lives with her boyfriend, David Doria, and their 1-year-old daughter in Kaneohe. "It kind of feels like we are married. We have the commitment, just not the marriage."

The couple, who both have jobs and met as students at the University of Hawaii at Hilo, feel no need to get married, but that may change in time, she said.

"I think I wanted to get a bit more comfortable financially," Sai said. "I think maybe eventually we will."

The tendency to have children outside of marriage has been building for a long time. In 1970, just 1 in 10 women who gave birth in the United States were unmarried. By 1985, it was 2 out of 10, and in 2000, it reached 3 out of 10. By 2010, 4 out of 10 women giving birth were unmarried.

In Hawaii, the nonmarital birth rate, at 37 percent of all births, is slightly lower than the national average of 41 percent, but is rising fast. Most births to single moms are not planned, but among women who cohabit roughly half are intentional, national data show.

"It used to be that ‘unwed mother’ and ‘teen mother’ were used interchangeably," said Stephanie Ventura, chief of the Reproductive Statistics Branch of the National Center for Health Statistics. "That’s not the case anymore because 64 percent of births to women 20 to 24 are unmarried, and even the 25-to-29 age group is 34 percent. In their 30s, it’s about 21 percent."

"They are definitely shifting to older ages," she added. "The social disapproval has dwindled. There is much more premarital cohabitation, and people are having babies in cohabiting relationships."

The increase in nonmarital births in the past decade has been fueled by women age 25 and up, birth records at the state Department of Health show. Younger women had a shrinking portion of the pie. Teen moms accounted for just 14 percent of out-of-wedlock births in Hawaii last year, a big drop from 21 percent a decade ago. Meanwhile, women age 30 and up produced a larger chunk of the nonmarital births, at 25 percent, up from 19 percent over the decade.

"With older women, we are hoping that those are more personal decisions that women are making, which then speaks to a kind of cultural shift," said Ivette Stern, project director for Hawaii Kids Count at the University of Hawaii Center on the Family. "If women are prepared, then it’s a personal choice."

Nonmarital births are commonplace for women of Hawaiian ancestry, accounting for 60 percent of their births in 2012, according to state Health Department data. Mothers of Filipino heritage had the next highest rate at 40 percent, followed by those with Japanese (22 percent), Caucasian (19 percent) and Chinese (16 percent) heritage.

While society has become more open to older women having children outside of marriage, the concern over teen pregnancy persists, and campaigns to reduce it are succeeding. The teen birthrate has been cut in half over the past two decades in the United States and reached a new low in 2011, according to a National Vital Statistics Report released last month.

"When it’s a teenage mom who hasn’t finished her education, who may not have the involvement of the father, children are at greater risk for some of the poor outcomes because the resources may not be there," Stern said.

Hawaii’s teen birthrate is just below the national average, at 30 births per 1,000 women ages 15 to 19. That figure dropped 23 percent between 2007 and 2011, in tandem with the national rate. The National Survey of Family Growth shows that teens are using more effective contraception, including dual methods.

THE SHIFT TOWARD older women giving birth outside of marriage has many roots. For one thing, women are getting married later in life these days. While the age at first marriage used to be lower than the age at first birth, the reverse is now true. The median age at first marriage in 2012 was 26, a year older than the median age at first birth, according to the National Center on Family & Marriage Research.

High divorce rates also play a role. Children whose parents have divorced might grow up jaded about marriage as an institution. Divorced women may forgo a second marriage but still have a child, figuring that marriage is no panacea.

Some older women haven’t found the right partner, but feel their biological clock ticking. Virginia Loo, an epidemiologist, watched as her older friends felt pressured to find a man and have a child as they progressed through their 30s.

"I saw a lot of them go in this panic as they got near 40 and they weren’t with a partner," Loo said. "The whole sequence of finding a person and then having a baby wasn’t going to be very viable. In some cases, I think they really were compromising what they were looking for in a partner, because of their biological time frame."

Financially secure and single, Loo decided to go solo as a parent. "When 35 rolled around, I said, ‘OK, I’m going to do it,’" she said. "It seems like it can be done in a responsible way."

Loo gave birth to a 9-pound, 15-ounce baby boy last fall. She is grateful for support from her family. Marriage might still be an option down the road.

"Having a kid first doesn’t seem to preclude finding a partner later," she said.

Some women not financially stable who have kids on their own rely on government assistance, although benefits have been cut and incentives reduced. Before welfare reform in 1996, benefits depended on having an absent or disabled parent. But Temporary Assistance to Needy Families is now based on low household income. It can go to intact families, married or not, and absent fathers are hit up for child support. Aid recipients must be working, seeking work or in training, and benefits are ended for life after five years.

"Once the primary adult, say the mom, accumulates her five years, that’s it," said Lorie Young, acting administrator of the financial assistance program at the state Department of Human Services. "Even if she had more kids, it wouldn’t matter, we would still end benefits for the entire family."

The more educated a woman, the less likely she is to have a child without being married. Nationally, just 9 percent of births to women with college degrees come outside of marriage, according to an American Community Survey report from the Census Bureau issued in May. Among women with less than a high school diploma, more than half of births are nonmarital.

Judith Clark, executive director of the Hawaii Youth Services Network, pointed to sex education as a major reason for the reduction in teen births here.

"One reason has been increases in comprehensive, balanced sexual health education for young people in Hawaii, both in school settings and in community-based programs," she said. "The other is that Hawaii has laws and policies in place that enable young people to have access to family planning and contraceptive services when they need it."