“Nulliparous” is a fancy medical word used to describe a woman who hasn’t given birth to a child.

It doesn’t necessarily mean that she’s never been pregnant — someone who’s had a miscarriage, stillbirth, or elective abortion but has never given birth to a live baby is still referred to as nulliparous. (A woman who’s never been pregnant is called nulligravida.)

If you’ve never heard the word nulliparous — even if it describes you — you’re not alone. It’s not something that’s tossed around in casual conversation. But it does come up in medical literature and research, as women who fall into this category may be at higher risk for certain conditions.

Multiparous

The term “multiparous” isn’t exactly the opposite of nulliparous — and it’s not always defined the same way. It can describe someone who’s :

  • had more than one baby in a single birth (i.e., twins or higher-order multiples)
  • had two or more live births
  • had one or more live births
  • carried and given birth to at least one baby that reached 28 weeks’ gestation or later

Regardless, though, multiparous does refer to a woman who’s had at least one live birth.

Primiparous

The term “primiparous” is used to describe a woman who’s given birth to one live baby. This term can also describe a woman experiencing her first pregnancy. If the pregnancy ends in loss, she is then considered nulliparous.

In studying Catholic nuns who abstain from sex, researchers have acknowledged that there’s a link between nulliparity and increased risk of reproductive cancers like ovarian and uterine cancer. The million-dollar question is why.

Originally, the link was attributed to the nuns having more ovulatory cycles in their lifetime — after all, pregnancy and birth control both halt ovulation, and the nuns experienced neither. But the truth is, there’s some disagreement about this.

Regardless of the reasoning, screening and early detection are important if you fall into the “nulliparous” category.

In observing health conditions in nuns over hundreds of years, researchers have found that nulliparous women also have a greater risk of breast cancer.

Childbirth is known to lower breast cancer risk later in life, especially for women who give birth at a younger age (under 30). On the other hand, women who’ve had a live birth have a higher short-term risk despite this longer-term protection.

Breastfeeding — an activity generally, but not always, limited to women who experience live birth — also reduces the risk of breast cancer.

What does this all mean for nulliparous women? Again, it doesn’t need to be a cause for panic. Breast cancer risk is very real for all women, and your best defenses are monthly self-exams and regular mammograms.

Nulliparous women have an increased risk of preeclampsia, a potentially life threatening condition in which you have high blood pressure and protein in your urine during pregnancy.

Preeclampsia isn’t too uncommon — just under 5 percent of all pregnant women experience it. While this isn’t great news, it does mean that OB-GYNs with experience in high-risk pregnancies are very accustomed to managing it in their patients.

If you haven’t previously had a child, your labor may take longer. In fact, doctors define “prolonged first-stage labor” differently for nulliparous and multiparous women. It’s defined as more than 20 hours in nulliparous women and as more than 14 hours in multiparous women.

One large registry study found that nulliparous women of advanced maternal age — that is, over age 35 — had a higher risk of stillbirth than those who had prior live births.

Some people used to believe that nulliparous women had a reduced ability to get pregnant after the removal of a long-term intrauterine device (IUD). But this was based on older research.

More recent research actually shows a lack of conclusive evidence of this. IUDs are a recommended form of birth control for all women, including those who haven’t had children.

If you haven’t had a biological child, you fall into the “nulliparous” category. Being nulliparous comes with certain risks — but it doesn’t mean you’re less healthy than your peers.

In reality, we all fall on a spectrum in which we’re at higher risk for some conditions and lower risk for others. Multiparous women, for example, may have a higher risk of cervical cancer.

You can lower your risk by doing regular screenings as recommended by your health care provider and keeping certain things in mind should you become pregnant.