Nulliparity, or never giving birth, can increase risk factors for certain cancers for women. Being pregnant and going through the labor process causes a rise and fall in hormones, some of which can be protective.
A nulliparous woman is someone who has not given birth to a child at 20 weeks' gestation or more.
Nulliparity puts a woman at risk for reproductive cancers like breast, ovarian, and endometrial cancer.
Women exposed to the hormones produced by the ovaries over long periods are at higher risk for breast cancer.
What is nulliparity?
Nulliparity doesn't mean that the woman was never pregnant. It means that she did not give birth to a child at 20 weeks' gestation or later.
There could be many reasons that a woman is nulliparous. The cause of nulliparity could be by choice, the use of abortion, infertility, or even due to miscarriage.
Regardless of the reason for being a nulliparous woman, certain situations can put this population at a greater risk for other conditions.
Risks of nulliparity
Pregnancy can be challenging on the woman's body, as the body works hard to create a baby. While the rise and fall of certain hormones can feel quite taxing, there are also many protective features that pregnancy can produce.
So what happens when you never give birth to a baby?
Being a nulliparous woman can put you at a higher risk for certain reproductive cancers. An established risk is already associated with breast, ovarian, and endometrial cancer, and these risks become reduced with each pregnancy.
Timing is always essential as well for reducing or increasing the risks. Having a baby for the first time at an older age increases the risk of developing breast cancer. The older you are when you have your last baby, the lower your risk of developing endometrial cancer.
When you are pregnant, your body releases hormones to protect the pregnancy. Some of the hormones released can also have extra protection for the mother.
Some studies reported that the progesterone produced during pregnancy has protective effects against the cancer cells by inducing apoptosis in the cancer cells. In other words, progesterone causes the cancer cells to eliminate themselves.
Another thought is that when a woman gives birth vaginally, this could help to shed the precancerous or cancerous cells from the uterus. This shedding of the cells would also apply to the period when the uterus begins to shrink and sheds its lining after birth.
While there seems to be good evidence that a nulliparous woman is at higher risk for reproductive cancers, there isn't an official answer for the exact reason.
Are nulliparous women less healthy?
Being nulliparous does not mean that you are less healthy. It just means that you carry a higher risk for reproductive cancers since your body hasn't experienced the protective factors of pregnancy.
However, one study found that nulliparous women who were overweight and had poorer vascular health might be at greater risk of cardiovascular disease compared to women of the same stature who had birthed.
Does nulliparity have a higher risk of breast cancer?
Women whose breast tissue comes into contact with estrogen and progesterone (the hormones produced by the ovaries) for extended periods have a greater chance of developing breast cancer.
Situations that may cause this more prolonged exposure to these hormones are:
- Having never given birth
- Starting your period at a young age
- First-time pregnancy at an older age
- The onset of menopause at an older age
Certain pregnancy-related factors can decrease the risk of developing breast cancer. Having a first full-term pregnancy at an early age, having multiple pregnancies, and breastfeeding for longer have been shown to decrease the risk of developing breast cancer.
Risks for nulliparous women during pregnancy
The most talked about risk for nulliparous women is reproductive cancers. Does this mean that there aren't risks for anything else? Being a nulliparous woman doesn't define your health status, however some areas of risk during your first pregnancy are:
- Pre-eclampsia. This disease is seen with new onset hypertension and protein in the urine, which can be very dangerous for mother and baby.
Complicated birth. Even when compared to women with multiple pregnancies and risk factors already present for a complicated birth, nulliparous women still had a considerably higher chance of having a complicated delivery.
Poor birth outcomes. One study emphasized that clinicians should be diligent in care for nulliparous women because they were at higher risk for preterm birth, low birth weight, and small for gestational age birth outcomes.
Other health factors such as poor nutrition, being overweight, and even genetics can increase the chances of developing these risks for nulliparous women. However, they can also be managed and detected early with close follow-ups by your doctor.
The simple fact is that being a nulliparous woman does not mean that you are guaranteed to develop any of these conditions. It just means that you should be aware of the possibility. Monitoring yourself for any concerning symptoms and having regular discussions with your doctor are essential steps to take in being proactive in your health.
- Journal of Cancer Prevention. Protective Effect of Progesterone during Pregnancy against Ovarian Cancer.
- Cancer. An Aggregated Analysis of Hormonal Factors and Endometrial Cancer Risk by Parity.
- Journal of internal medicine. The Role of Pregnancy, Perinatal Factors, and Hormones in Maternal Cancer Risk: A review of the evidence.
- National Cancer Institute. Reproductive History and Cancer Risk.
- BMC. Parity and the risks of adverse birth outcomes: a retrospective study among Chinese.
- Obesity. Nulliparity is associated with less healthy markers of subclinical cardiovascular disease in young women with overweight and obesity.
- BMJ. Risk of complicated birth at term in nulliparous and multiparous women using routinely collected maternity data in England: cohort study.