The number of American women without children has risen to an all-time high of 1 in 5, a jump since the 1970s when 1 in 10 women ended their childbearing years without having a baby, according to the Pew Research Center.
About 1.9 million women aged 40-44%E2%80%94or 18 percent%E2%80%94were childless in 2008, an 80 percent increase since 1976, when just 580,000%E2%80%9410 percent of those in that age bracket%E2%80%94had never given birth, the Census Bureau's Current Population Survey shows.
Childlessness has increased across racial and ethnic groups and most education levels, but has dropped among women with advanced degrees in the past decade, according to the research.
Part of the reason for the rise in the number of childless women is an overall pattern toward delaying marriage and having kids, the research showed. Experts say that a drop in societal pressure to be a parent is also responsible for the trend, along with an increase in career opportunities and an improvement in birth control options and effectiveness.
"People put off getting pregnant," said women's health expert Dr. Laura Corio, a member of AOL Health's Medical Advisory Board. "Even when they're married they're putting off getting pregnant. Then they wake up one day and they're 40 and they want to have a child. It's like, hello?"
Explanations for the trend vary, but for some, the reason behind delaying parenting is a simple joie de vivre.
"They're freer. People are enjoying their lives: they're traveling, shopping, eating out," Corio told AOL Health. "Putting a baby into the situation is going to change everything."
Though the most educated women are still among those most likely to never give birth, there was a 31 percent decline in those aged 40-44 with master's, doctoral or professional degrees who had not had babies between 1994 and 2008, when 24 percent of women in that category were childless.
The data represents combined statistics from 2006 and 2008 (referred to as 2008 in the study) and from 1992 and 1994 (referred to as 1994).
White women remain the most likely not to have had a child, but the childless rates have grown more quickly for blacks, Hispanics and Asians over the past decade, according to the figures.
Never-married women still had the highest incidence of childlessness, though those rates also have declined over the past 10 years. By comparison, the childless rates have increased for those who are married or were at one time referred to as the "ever-marrieds."
"A lot of women can't find someone, or they're very picky or very educated," Corio said. "Contraception is also better. A lot of pregnancies in the past may have been accidents where they decided to keep the baby. It's also money - they think, we're not in the financial situation [to have children]."
Among the women aged 40 to 44 without children, the number of those who didn't want to have children equaled the number of those who did but weren't able to conceive, according to figures from the National Survey of Family Growth.
In 2003, about 6 percent of women in that age group were voluntarily childless, 6 percent were involuntarily childless and 2 percent didn't have children but wanted them in the future.
Along with the population changes have come shifts in attitude, with public opinion showing more acceptance of women without children, Pew Research reported. Most adults - 59 percent in 2002 - said they disagree with the statement that people who don't have kids "lead empty lives," compared to only 39 percent who didn't agree with the statement in 1988.
Similarly, a 2007 Pew survey showed that 41 percent of adults believe children are important for a successful marriage, down from 65 percent who expressed the same views in 1990.
About 46 percent of people said the trend has no bearing on society, according to a 2009 Pew survey, but 38 percent said it was bad for society -- up from 29 percent in 2007.