Fertility might decline in a woman’s 30s, but that hasn’t stopped more females from having children during this time than in their 20s, reports the Associated Press. The Centers for Disease Control released preliminary data Wednesday showing that the birth rate for women between 30 and 34 years old was 103 for every 100,000. Meanwhile, the number for females 25 to 29 was only 102 per 100,000.

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The CDC also found that the decline in teen birth rates dropped last year as well as the overall birth rate. In 2016, the CDC reports there were 62 births for 100,000 women between 15 to 44 years old. Women are now having their first child at 28, up from the average age of 26 in 2013.

The older age for getting pregnant reflects the larger trend of people putting off marriage. Many are choosing to advance their careers before settling down with a family, putting the average age of marriage to 27 years old.

According to the American Congress of Obstetricians and Gynecologists, a healthy woman of childbearing age has about a 20 percent chance of getting pregnant in any given menstrual cycle. However, this starts to decline in a woman’s early 30s. Once a female hits 37, the rate declines even more quickly.

Egg freezing, however, is gaining in popularity as more women look towards medical advances to keep their options open. As we previously reported, the method doesn’t come cheap. There’s an initial fee for egg retrieval, which can reach upwards of $10,000. Drugs, plus a yearly storage fee add to the price tag.

There are several causes of infertility, according to the Mayo Clinic. Ovulation problems which can hinder the eggs being released is one. Polycystic Ovary Syndrome can impact ovulation. Cervical abnormalities, damaged fallopian tubes, endometriosis and undergoing cancer treatments are other causes.

While there is no bulletproof way to ensure you can have kids, certain lifestyle behaviors can impact fertility. Outside of age, smoking by either gender can reduce your chance of getting pregnant, and the hospital writes that miscarriages are more common in females who smoke. For men, smoking can increase his chances of having low sperm count and erectile dysfunction. Being under- or overweight can also impact fertility.

Read: Fertility 2017: Millennial Women Delay Marriage, Choose Egg Freezing To Allow Later Pregnancy

The Mayo Clinic advises seeing a doctor for infertility after you’ve been trying to conceive for a full year without success. However, women who are 35 and older will want to go after six months of failed attempts. After determining that the reason is due to fertility, both women and men have several treatment options. Medication could help boost sperm count in both genders. According to the CDC, about 11 percent of women between 15 to 44 have used infertility services.

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