"A lot of us live our lives with a 'wait and see' approach, so we're letting women know there are more options to having greater control there," said Afton Vechery, CEO and co-founder of start-up Modern Fertility in San Francisco.

The tests provide a small snapshot of a woman's reproductive health. But the insight they provide may help some avoid heartache later in life by choosing to freeze their eggs or speed their baby plans.

The global fertility test market is estimated to grow at an annual rate of 7.2 percent over the next five years — from $411.8 million this year to $583.1 million by 2023, according to market research firm Research and Markets in Dublin, Ireland.

As more women put off starting families and U.S. fertility rates drop, helping women assess how much time, and how many eggs, they have left to conceive is a growing business. The market for ovulation tests, fertility monitors and other mail-in home tests to help women up their odds of bearing fruit is exploding. Several startups are selling kits that allow women to test their fertility at home with a simple finger prick.

After a year of trying, she saw a doctor who told her she should be fine at her age, Deymier said. After another year, she saw a fertility specialist. Her tests all came back normal. Her doctor prescribed clomid, an oral medicine to stimulate ovulation, and she tried intrauterine insemination. But she still could not conceive.

Alix Deymier was young and healthy when she and her husband first tried getting pregnant at 25. So she thought it would be easy.

More women are delaying pregnancy, whether for career, financial, personal or other reasons. Last year, U.S. birth rates dropped in every age group from 15 through 35 — while birth rates among women of "advanced maternal age" (over 35) rose, according to provisional data from the Centers for Disease Control and Prevention. The group of women with the largest rise in birth rates was 45 and older.

Unlike men who continually replenish their supply of sperm, women don't make more eggs. Girls are born with their lifetime supply and shed them as they age. While some women lose their eggs faster than others, all women see their fertility prospects rapidly diminish beginning in their 30s.

Women can undergo tests at their doctor's office to assess fertility factors, but they typically don't unless they're struggling to conceive and it may not be covered by insurance if they haven't been diagnosed with a problem. At-home testing opens the opportunity for more women to gauge their reproductive health.

The reasons for why women might take these tests varies. Some women may want to know their chances of becoming pregnant soon, while others may want to know how many eggs they have available to freeze to use later or their odds of success with fertility treatments like in vitro fertilization.

Modern Fertility is just one of several companies selling ovarian reserve tests. Everlywell, Let'sGetChecked and Future Family, among others, also sell the kits that can be purchased online and taken at home for $79 to $199.

Modern Fertility allows women to send a blood sample drawn by pricking a finger or having blood drawn at a lab and tested at Quest Diagnostics. The at-home test is mailed back and then screened. The company says there's no difference in the accuracy of the results, which show how a woman's ovarian reserve compares with her age group.

To be sure, researchers say women with low egg counts, as indicated by low anti-müllerian hormone values, were almost as likely to become pregnant as women with normal egg counts for their age. The study, published last year in the Journal of the American Medical Association casts doubt on whether women should base life-altering choices on tests that measure just a handful of hormones.

Egg count is a "very important" part of fertility, but it's just "one part of a very complex process," said Dr. Zev Williams, chief of the Division of Reproductive Endocrinology and Infertility at Columbia University Medical Center.

A woman may have a healthy number of eggs available, but she could experience other problems, such as blocked fallopian tubes, which prevents eggs from releasing and being fertilized.

"Increased communication about fertility is overall a good thing, but I wouldn't want people to be falsely alarmed or falsey affirmed by one single blood test," said Dr. Williams, who's also an associate professor of obstetrics and gynecology at the university.

Deymier, now 34 and in a long-distance relationship, knows it will be another few years until she will likely try to get pregnant again. She saw an advertisement for Modern Fertility on Facebook in March and after a few days of thinking, decided to take the test, she said.

Her hormone levels indicated she may have a low egg count for her age. She set up a call with a nurse through Modern Fertility then brought her results to her gynecologist, who referred her to a fertility specialist. She now has an appointment scheduled to discuss her options, including freezing her eggs, she said.

"I don't think I would've made an appointment without this information, and maybe then I would've had a much slimmer chance," said Deymider, an assistant professor in biomedical engineering at the University of Connecticut in Hartford.