The word has Latin roots, from “null” meaning “not” and the verb “parere,” meaning “to bring forth.” Nulliparous women are at greater risk for some health conditions, including breast and reproductive cancers. And among nulliparous women age 35 and older, there’s a greater risk of having a stillborn baby, according to a study of 1.8 million pregnancies reported in the journal Obstetrics & Gynecology.

Reproductive Cancers

For decades, the scientific community has known nulliparous women have an increased risk for cancers of the reproductive system, including ovarian and uterine cancers. The increased risk was thought to be due to the fact that people who have been pregnant have fewer ovulatory cycles.

Breast Cancer

Women who have children before the age of 20 have a lower lifetime risk of breast cancer compared to their nulliparous counterparts, but young mothers have a higher risk for the first 15 years after their pregnancy. Mothers with five full-term pregnancies are about 50% less likely than nulliparous women to develop breast cancer. Breastfeeding, which nulliparous women don’t experience, also has been found to reduce the risk of breast cancer.

Infertility

Early research on IUD use among nulliparous women suggested that it was more difficult for them to become pregnant for the first time following the long-term use of an IUD (intrauterine device). This was compared to the use of a barrier method, such as a diaphragm or condom.  More often nulliparous women were likely to have had exposure to more sexual partners, and therefore more likely to have been exposed to a sexually transmitted disease (STD). Infertility is a side effect of many STDs.

Labor

The stages of labor during birth have different norms for people who have previously given birth and people who haven’t (nulliparous women). For first births, the latent stage (when there are mild and infrequent contractions) is about 1.5 hours longer, the active labor stage is almost 2 hours longer and the second stage (the time between when the cervix dilates completely and the baby comes out) is about 50 minutes longer.