This article originally appeared on Healthline , the world’s second-largest health information website, which brings you transparent health information so you can make confident decisions for living well.

Millennials are blamed for a lot of things.

They killed landline phones. They destroyed movie rental stores. They even get flack for the decline in bar soap use.

Now they might be getting credit, whether fair or not, for the decline in the birth rate in the United States.

Advertisement:

Indeed, the country just recorded its lowest birth rate in 30 years.

Millennials (people born from 1981 to 1996), who were once part of the largest post-baby boomer era birth increase, are now one part of the continuing drop in the U.S. birth rate.

Data from the Centers for Disease Control and Prevention (CDC) showed that America’s 3,853,472 births in 2017 was the lowest since 1987. That’s down 2 percent from the previous year, continuing a trend of fertility rate decline during the past decade.

Advertisement:

Read more Healthline: Does Being Around a Baby Boost Fertility?

In addition, the United States is now further away from a viable replacement rate — that is, the number of births necessary for a generation of people to replace the number of people dying. That number has been slipping since 1971, according to the CDC.

To replace the population, the United States needs about 2,100 births per 1,000 women.

Advertisement:

The total fertility rate (or the total number of children women will have in their lifetimes) in 2017 was 1,764.5 births per 1,000 women. That represents a 3 percent drop from the year before and the largest single-year decline since 2010.

The number of births in 2017 also represents a decade’s long fall from 2007, the year the United States broke its highest yearly birth rate record with 4.3 million births. That record had been held since the post-World War II baby boom era.

Advertisement:

In 2008, America hit one of its steepest economic declines in decades. That recession may have prompted young adults to delay having children due to money concerns.

“There are many factors that contribute to the low birth rate, but it mostly comes down to choice and lifestyle factors,” Dr. James Grifo, a specialist in reproductive endocrinology and infertility at NYU Langone in New York and chief medical officer for Prelude Fertility, told Healthline.

“Economics, alternative lifestyles, waiting to find the optimal partner, building a career — these all factor into delaying childbirth or couples having fewer children.”

Advertisement:

In short, the decreasing birth rate in America is a multifaceted problem.

Waiting to get married

Individuals are waiting longer to get married than their parents or grandparents.

In fact, according to the U.S. Census Bureau, marriage ages are the highest they’ve ever been, with women marrying on average at 27 years of age and men at 29 years old.

Advertisement:

For comparison, the average age for women to marry in 1980 was 22.

However, the nation’s divorce rate is also declining, in large part thanks to millennials who aren’t divorcing at rates near previous generations, especially baby boomers.

Waiting longer to have children

Waiting to have children can also reduce the number of children you have.

Advertisement:

“If you’re not having your first child until you’re 37 or 38, you have less time to have a big family,” said Dr. James Stelling, a double board-certified physician in obstetrics and gynecology and reproductive endocrinology and infertility at Advanced Specialty Care, a Stony Brook Medicine facility, in New York.

“If you don’t have an unplanned pregnancy at 21, you don’t have your third at 25. It’s the decline of the mega family,” Stelling told Healthline.

Financial concerns

Children aren’t cheap, and the costs of raising children are still climbing.

Advertisement:

As of 2015, the average annual child-rearing expense estimates ranged from $12,350 to $13,900 for a child in a family with two children and married parents. That puts the total price tag for child-rearing until 17 perilously close to a quarter of a million dollars.

“For some couples, it’s about financial security,” Grifo said.

“They understand it’s expensive to have large families and want to be in a strong financial position before embarking on parenthood.”

In addition, many individuals leave college today with tens of thousands of dollars in student loans. Some also face real estate markets that are exorbitantly high, if not entirely out of reach.

Advertisement:

“These generations [millennials and iGeneration] have lived, for a large portion of their life, in recession,” Dr. Janelle Luk, a reproductive endocrinologist and infertility specialist and co-founder of Generation Next Fertility in New York City, told Healthline.

“Because of this, a lot of them have lasting economic insecurity, which has caused them to choose to delay parenthood.”

Career focus

It appears women want to establish their careers before embarking on motherhood.

Some recent statistics back that theory up.

In 2017, women in their 40s were the only group with a higher birth rate.

Birth rates for women in their 30s, which had been rising in recent years, fell 2 percent.

“Women over 35 years old have shown an increase in first-time births,” Luk said.

“It’s not that we’re seeing the lowest birth rate in 30 years, but rather a changing demographic of mothers. This is due to the increase of women pursuing higher education and careers. Economically and societally, this has impacts, of course.”

The effect of fertility treatments

Because couples are waiting longer to have children, their window of fertility might be shorter.

Plus, the delay for children can sometimes result in infertility, as fertility significantly declines as women approach 40.

“Most patients think infertility is not going to happen to them,” Stelling said.

“They know that contraception is really good. They didn’t accidentally get pregnant when they were 25 years old, and they don’t think it’s going to be hard to get pregnant at 35.”

When pregnancy feels out of reach, women with the means to seek fertility treatment often turn to experts such as Stelling for help starting their families. Of course, that often comes with a price tag.

“For many women, it’s one child and done. Or they kind of want twins because that’s a bit like one-stop shopping,” Stelling said.

Read more Healthline: New Theory on Why Fertility Declines with Age

He notes that differing requirements between states mean some individuals have health insurance coverage for fertility treatments while people in other states don’t.

Despite the financial considerations, more individuals and couples are seeking out fertility treatments, as improvements have made conception easier than even just a generation ago.

“The medications and procedures like intrauterine insemination and in vitro fertilization that we use have been incredibly successful at helping couples conceive,” Dr. Albert Hsu, a reproductive endocrinologist with University of Missouri Health, told Healthline.

“On the one hand, infertility treatments have been incredibly successful at helping couples with fertility issues conceive. This has been an enormous benefit to society and has likely helped to keep our birth rates from sliding even further,” Hsu said.

Of course, the impact of fertility treatments has had some negative consequences, too.

“On the other hand,” Hsu added, “the stories of 50-plus-year-old female celebrities having children has not been a service to the general public, as I regularly have 45-year-old women who request an infertility workup.

“Unfortunately, it gets increasingly difficult to conceive a pregnancy and live birth after the age of 40. When you hear that a 50-year-old woman has just had a live birth, that is almost always as a result of IVF with donor eggs.”

Contraception works

Most pregnancies in the world still are unplanned, Stelling said.

But the rates of unplanned pregnancies are dropping as contraception use is rising.

Between 2002 and 2017, the number of people who were using any type of contraceptive method rose from 62 percent to more than 63 percent.

“Women have access to better contraception and longer-term birth control like IUDs,” Stelling said.

“Plus, good sex education is improving and leading to fewer unplanned pregnancies.”

However, the use of the pill, condoms, female and male sterilization, hormone shots, and even withdrawal methods have fallen.

The largest increase in contraception use was with the long-term intrauterine device (IUD). Rates of IUD use rose from about 1 percent in 2002 to more than 8 percent between 2015 and 2017.

An issue in many countries

The United States isn’t alone in this birth rate conundrum.

Developed countries such as Greece, Spain, and Japan have been dealing with steadily declining birth rates for decades.

In fact, Japan has its lowest birth rate in history.

In 2018, the country had 921,000 births but 1.37 million deaths. That was 25,000 fewer births than in 2017 — and the lowest number recorded for the Pacific island nation since it began keeping records in 1899.

Japanese government officials have made an effort in recent years to encourage Japanese families to have more children. So far, their efforts don’t appear to be working.

In South Korea, a similar picture is unfolding.

That country’s population will begin decreasing over the next 10 years, as deaths outpace births. There, the government has stepped in with cash subsidies and changes to workweek hours to help couples accommodate raising families. Their efforts also seem to be ineffective.

China’s birth rate just hit a 70-year low, too.

The effect in the United States

“Recent reports have indicated that the gap between the number of children that women want to have and the number of children they will actually have is the highest it has been in 40 years,” Luk said.

“That leads us to believe that they will likely have fewer children than women of previous generations.”

Those older parents, however, may have some benefits for society as a whole, Dr. Daniel Kort, a double board-certified OB/GYN and reproductive endocrinologist with Neway Fertility in New York, told Healthline.

“While older parents have many disadvantages — energy and activity levels, overall lifespan, etc. — they also have some advantages — financial resources, life experiences,” Kort said.

“While there is no clear best age to have and take care of children, the age of the parents clearly affects the children and their upbringing in different ways.”

As America’s demographics continue to change, the landscape of the country’s population changes with it.

Fertility rates vary by region. States with some of the lowest birth rates include New York, California, Oregon, and Colorado.

Indeed, only two states — South Dakota and Utah — have total fertility rates that help them sustain their current population.

South Dakota edged out Utah with 2,227 births per 1,000 women. Utah had 2,120 births per 1,000 women. Idaho, North Dakota, and Nebraska all have fertility rates over 2,000.

Washington, D.C., had the lowest total fertility rate, with 1,421 births per 1,000 women.

The U.S. Census Bureau says immigrants will be the largest driver of the U.S. population as early as 2027. That’s the year international migration to America is expected to surpass the country’s natural increase in population.

The bottom line

The United States, like several other developed countries in the world, stands at the precipice of shifting demographics and population changes.

The U.S. birth rate continues its steady decline as Americans put income stability, economic opportunity, and other factors before starting a family, a shift from previous generations.

This leaves individuals and families to start child-rearing at an older age.

It also cuts off the years of fertility that are possible for many couples. As a result, families are having fewer children, and the average family size is shrinking.