Here's when women need to start thinking seriously about their fertility

Many young women assume that they won't have to think about fertility until they're older (as in, mid-30s and beyond). Instead, they may spend their 20s and early 30s more focused on contraception and actively avoiding pregnancy than thinking about having children.

However, those who hope to one day have children should start talking to their doctors about fertility a lot earlier than they think, according to Dr. Shruti Malik of Shady Grove Fertility in Virginia.

Those conversations need to start by age 30, the fertility expert revealed.

"The best chances for women to conceive are going to most often be in their 20s or potentially even their early 30s," Malik told INSIDER. "Female fertility starts to decline in the early 20s, but conception rates are still really high even into their 30s. So, it's most notably the age of 35 that most women associate with that initial decline in fertility."

According to the Centers for Disease Control and Prevention, women are waiting longer than ever to give birth to their first child. The average age for a first time mom in the US increased from 24.9 in 2000 to 26.3 in 2014. Furthermore, the CDC found that the proportion of women aged 30-34 giving birth for the first time rose by 28 percent from 2000 to 2014- and first births to women age 35 and older rose by 23 percent.

And so, Malik recommends that women start talking to their doctors about fertility in their 20s if they have a family history of early menopause or infertility, or suffer from irregular periods or conditions that may affect their fertility.

Otherwise, women should begin the discussion by age 30, she noted. Around that age, women who are waiting to have children may also want to consider freezing their eggs before their fertility begins to rapidly decline.

The process, which usually costs around $7,000, entails taking fertility medication and inducing ovulation, and then retrieving, freezing and storing eggs. Annual storage fees typically run around $200.

"We're definitely seeing a very big increase in the number of women that are considering egg freezing, and I think it's great, because it really enables women to have the freedom to make plans for their future," Malik said.