Both breast cancer and fertility are frequent concerns for women, and recent research offers evidence of the complex relationships among fertility, infertility, fertility treatments, childbirth, and cancer. Several studies reveal that age may be the decisive factor in the puzzle of breast cancer risk for some, including the age a woman gives birth and the age when she undergoes infertility treatments.
Childbirth and breast cancer risk
According to research from the Susan G. Komen foundation, women who give birth to their first child before age 35 have a lower overall risk for developing breast cancer. Interestingly, however, pregnancy increases risk of breast cancer in the short run, owing to hormonal fluctuations associated with pregnancy and childbirth.
Women who give birth to their first child after age 35 compared to women who give birth by age 20 have a 40% greater likelihood of developing breast cancer. Because breast cells grow faster during pregnancy, if there is pre-existing genetic damage, which is more likely as a woman ages, the growth of damaged cells increases the risk of the growth of cancerous cells.
Infertility treatment and breast cancer risk
Interestingly, there is a reverse corollary with age and infertility treatments than we see with childbirth. Research from the Breast Cancer Fund shows that women younger than 24 undertaking infertility treatments (including in-vitro fertilization – IVF – and associated drug treatments such as gonadotropins or clomiphene citrate) have statistically significant increases in the rate of breast cancer.
However, the same research found that for women age 40 or older who experience ovarian infertility and undergo pharmaceutical therapy and associated IVF had no greater risk of developing breast cancer than women who didn’t experience infertility treatments. Ironically, the success of IVF is generally better for women who are younger, but the subsequent breast cancer risks for them may be higher.
Age matters for fertility, IVF, and breast cancer risk
In summary, for those who can have a child without fertility treatments, research shows that giving birth younger offers decreased long-term breast cancer risk. But for those who cannot give birth without the assistance of infertility treatment, waiting until age 40 may lower the risk of breast cancer resulting from pharmaceutical therapy and associated IVF.
Unfortunately, other research indicates that the younger a woman is when she undergoes IVF, the greater the likelihood of successful childbirth from the procedure. For women under age 35, the live birth rate for an IVF procedure is 42% while for women age 35-37, the live birth rate drops to 35% and for women age 38-40, the success of IVF drops to an average of 26%.
Further compounding the concerns, as shown in research from the University of Rome, is that the more IVF cycles a woman undergoes, the lesser the risk of breast cancer. For women experiencing infertility, these are all valid concerns to evaluate before beginning a program of infertility treatment, particularly if there are other breast cancer risks such as BRCA1, BRCA2, or PALB2 genes.
Balancing the desire for childbirth with long-term health will become an increasing concern as many women choose to delay childbirth.