One in eight American women will develop breast cancer in her lifetime
About 2.38 percent of women develop breast cancer by age 50
Having children lowers the risk of breast cancer over the course of a woman’s life
But having a child actually raises cancer risk before 50 by 80 percent, a new University of North Carolina study reveals
The risks don’t seem to apply so much, however, to women who have a child before 25, though the reasons are not yet clear
Having a child may raise a woman’s risk of getting breast cancer before age 50 by 80 percent, a new study suggests.

Giving birth – especially more than once – has long been thought to help protect women against breast cancer by making changes to mammary gland cells that make them less susceptible to cancer.

But the relationship between age, childbearing and breast cancer is a complicated one.

A new study from the University of North Carolina warns that women who have children, especially after age 25 may actually be at a higher risk of breast cancer earlier on and won’t glean the protective effects of childbearing for some 20 years.

Breast cancer is second to only skin cancer as the most commonly diagnosed form of the disease in women.

About one out of every eight women will have breast cancer at some point in her life.

It’s a very real possibility that women live in fear of, and may even shape major life decisions, as it did for Angelina Jolie, who had preventative double mastectomies after discovering she carried the BRCA1 gene in 2013.

The gene is hardly a pure predictor of breast cancer – and none of the other risk factors for the disease.

Older age is another key factor, but the age a woman is when she has her first child and the number of children she has also must enter the calculation of breast cancer risks.

And that calculation is perhaps more complicated than we once thought, as confirmed by the new research.

Paradoxically, breast cancer risks increase in the short-term after a woman has her first child, then decrease over the long-term for those who have given birth.

It isn’t exactly clear what underlies this pattern.

The hormone estrogen has long been implicated in breast cancer risks.

Excess exposure to it before puberty (when it naturally surge) can raise breast cancer risks, as can exposure to estrogen taken as part of long-term hormone replacement therapy after menopause.

But somehow pregnancy, another period of estrogen increases, has protective effects.

The prevailing theory is that estrogen has an effect on breast cells in such a way that it can derail their DNA and turn them cancerous, but something about the changes mammary glands undergo in pregnancy somehow makes them protective against breast cancer – but we don’t yet no know why

Breastfeeding reduces a woman’s risk of breast cancer, a report suggested in August 2017.

For every five months a woman breastfeeds, her risk of developing breast cancer is lowered by two percent, a study review found.

Researchers believe breastfeeding protects women against the condition as it makes them temporarily stop getting periods, which reduces their lifetime exposure to the hormone oestrogen.

High oestrogen levels have previously been linked to developing breast cancer.

Breastfeeding may also help to remove cells with damaged DNA that may otherwise lead to tumor onset.

The researchers, from the American Institute for Cancer Research and the World Cancer Research Fund, analysed 18 studies that examined breastfeeding.

Of these, 13 investigated the effects of the length of time spent lactating.

The report also found that carrying excess weight after menopause increases a woman’s risk of developing breast cancer, yet it is protective while women are still able to conceive.

For both pre- and postmenopausal women, alcohol increases their risk of breast cancer and exercise reduces it, the report adds.

Babies who are breastfed are also less likely to gain weight in later life, the study found.

Study author Alice Bender said: ‘It isn’t always possible for moms to breastfeed but for those who can, know that breastfeeding can offer cancer protection for both the mother and the child.’

It’s also unclear why there is a spike in breast cancer risk after a woman’s first child – but a decline in the same risk with each subsequent childbirth.

To further investigate this pattern, the University of North Carolina (UNC) researchers analyzed data on 889, 944 women looking for patterns in their breast cancer risks.

In an effort to better pin down the particular relationships between childbearing and breast cancer, the UNC team also weighed the other risk factors in the women’s life, such as her family history of the disease.

Breast cancer also becomes much more common in women over 60, so they separated out those who got breast cancer by age 55 and those who developed it later.

Among women who were diagnosed at or before they were 55 had their peak breast cancer risk five years after giving birth.

Risks for women who had had children were 80 percent higher among women who had had children than for those that were not mothers.

And up to age 50, breast cancer remained notably higher among mothers than childless women.

For example, for every 100,000 women, there were 247 more cases of breast cancer by age 50 among those who had had children in the last three to seven years than those without.

But the key point to underline i that ‘in this age group, breast cancer is uncommon,’ said study co-author and UNC epidemiologist Dr Hazel Nichols.

‘The risk of developing breast cancer is still low overall, even if you’ve had a child five years ago.’

About 2.4 percent of women get diagnosed with breast cancer by age 50. By age 60, the rate rises to 3.56 percent.

Risks remained lowest for those who had children by age 25. risks were higher for those who gave birth for the first time after age 35.

Breast feeding is considered protective against breast cancer, too, but the UNC study uncovered no pattern in results related to breast cancer.

Once women reach 60, however, having had children does impact their breast cancer risks, helping to curb them.


‘This is evidence of the fact that just as breast cancer risk factors for young women can differ from risk factors in older women, there are different types of breast cancer, and the risk factors for developing one type versus another can differ,’ Dr Nichols said.