Does having children later in life increase your risk of breast cancer?

As more women choose to delay motherhood for personal, professional or financial reasons, questions around the impact of later-age pregnancies on long-term health, particularly breast cancer risk, are more relevant than ever.

According to Associate Professor Sanjay Warrier, age at first childbirth is indeed a significant factor in a woman's risk profile for developing breast cancer.

"Yes, the evidence shows that having children later in life can increase your risk of breast cancer," Associate Professor Warrier said. 

"But it's important to understand the underlying biology and context. It's not about blame, it's about being informed."

Associate Professor Warrier is one of the world's leading breast health and breast cancer surgeons who has built a highly respected practice in Sydney.  The practice spans three locations with its main surgical centre located at the Chris O'Brien Lifehouse in Camperdown, and the other sites at BMA House, Macquarie Street, Sydney and Bondi Junction Medical, Oxford Street, Bondi Junction.

In addition to Associate Professor Warrier's breast health and surgical work, he also dedicates considerable time to research exploring and developing advancements in breast cancer detection and treatments to improve outcomes for patients.  He also codeveloped Australasia's first Master of Advanced Surgery (Breast Surgery) which is delivered through the University of Sydney. 

Associate Professor Warrier outlines why age at first birth matters.

Hormonal exposure over time

"The longer a woman goes without experiencing the hormonal shifts of pregnancy, the longer her breast tissue is exposed to estrogen and progesterone. Prolonged exposure to these hormones is associated with an increased risk of hormone-receptor-positive breast cancers," Associate Professor Warrier said. 

Pregnancy-induced breast cell changes

"Pregnancy causes permanent changes in the structure and function of breast cells," Associate Professor Warrier said. 

"The earlier these changes occur, the more protective they are over a woman's lifetime."

Early pregnancies prompt breast cells to fully mature, reducing the likelihood of DNA mutations that could lead to cancer. Delaying this process means more years in which immature breast cells can potentially undergo harmful changes.

Risk is higher for first births after age 35

"Research indicates that women who have their first child after the age of 35 have a slightly higher risk of developing breast cancer compared to those who give birth before age 25. While the risk is modest, it's still a relevant factor when considered alongside other lifestyle or genetic risks," Associate Professor Warrier said. 

Other factors matter more 

More importantly, lifestyle factors such as alcohol consumption, weight, physical activity and family history can play an even more significant role in breast cancer risk than timing of childbirth alone.

"Age at first pregnancy is just one piece of the puzzle," he said. 

"Regular breast checks, screening from the recommended age and a healthy lifestyle are all essential to lowering your risk."

Be proactive about your breast health 

"If you do choose to have children later in life, it's crucial to be extra vigilant," Associate Professor Warrier said. 

• Undertake regular self-breast examinations at home
• Stay up to date with mammograms and medical screening as recommended for your age group
• See your GP or specialist regularly, especially if you have a family history of breast cancer
• Live well: eat a balanced, whole-food diet, stay physically active and prioritise sleep and stress management
• Avoid known risk factors such as smoking, vaping, excessive alcohol consumption and diets high in processed foods and sugars

"Being proactive can make all the difference.  Knowledge is power and prevention is key," he added. 

Further information about undertaking breast screening and detecting breast cancer can be found at https://www.drsanjaywarrier.com.au.

About Associate Professor Sanjay Warrier

Associate Professor Sanjay Warrier is a past President and current committee member of Breast Surgeons of Australia and New Zealand (BreastSurgANZ). His views are those of his own, not BreastSurgANZ. Associate Professor Warrier's surgery is located at the Chris O'Brien Lifehouse and he also has clinics at Oxford Street, Bondi Junction and Macquarie Street, Sydney. He is published in numerous peer-reviewed journals and won the Royal Prince Alfred Hospital's Patron's Prize for best scientific research.