FERTILITY, PREGNANCY AND BREAST CANCER

A diagnosis of breast cancer can be particularly confronting for women who are still planning to have children or who are currently pregnant. Many women immediately wonder whether treatment will affect their fertility, whether pregnancy will still be possible in the future, or whether trying to conceive after treatment could increase the risk of cancer returning. 

The reassuring news is that many women can still have children after breast cancer treatment, and research continues to improve fertility options and pregnancy outcomes for women diagnosed during their reproductive years. Breast cancer can also occur during pregnancy, although this is uncommon, and specialised medical teams work carefully to protect both mother and baby, emphasising the importance of tailored pregnancy and breast cancer treatment. 

Understanding the relationship between fertility, pregnancy and breast cancer can help women make informed decisions about treatment and future family planning. This guide explains how breast cancer treatments may affect fertility, options such as egg freezing and IVF, pregnancy after treatment, and the specialist care available in Australia.  

How Breast Cancer Treatment Can Affect Fertility 

Some breast cancer treatments can affect the ovaries and the body’s ability to conceive. However, the impact varies widely depending on factors such as age, the type of treatment used, and how the ovaries respond. 

Chemotherapy and fertility

Chemotherapy works by targeting rapidly dividing cells. While this is effective against cancer cells, it can also affect healthy cells, including those in the ovaries that produce eggs. Different chemotherapies impact the ovaries to varying degrees. As a result, some women may experience: 

• Temporary infertility 
• Reduced fertility 
• Permanent infertility in some cases 

Younger women generally have a higher chance of ovarian recovery after treatment compared with older women. 

Some women also experience early menopause, particularly if chemotherapy significantly affects ovarian function. 

Breast cancer treatment can also delay pregnancy plans. For some women, treatment may continue for several years, particularly if hormone therapy is recommended after chemotherapy or surgery. This delay can reduce fertility opportunities over time, especially as natural fertility declines with age. Discussing future family plans with your healthcare team before treatment begins can help you understand your options and consider fertility preservation if appropriate. 

Tamoxifen and fertility

Tamoxifen is a hormone therapy commonly used to reduce the risk of breast cancer returning. It is typically taken for five to ten years, which can delay pregnancy plans as pregnancy is not recommended whilst taking tamoxifen. 

Because fertility decisions are time-sensitive, it is important to discuss fertility preservation before breast cancer treatment begins. 

Research improving fertility options 

Australian researchers have played an important role in improving fertility outcomes for women with breast cancer. The POEMS clinical trial, led by Breast Cancer Trials, showed that a medication called Zoladex (Goserelin) can be used to temporarily suppress ovarian function during chemotherapy and help protect fertility in some women. 

This research has helped expand options for women who hope to have children after treatment. 

Women are also encouraged to explore resources from organisations such as Cancer Australia and Breast Cancer Network Australia (BCNA) when considering fertility planning. 

Early Menopause and Breast Cancer 

Some women experience early menopause as a result of breast cancer treatment. 

Early menopause occurs when the ovaries stop functioning before the age of 45. Chemotherapy can damage ovarian tissue, reducing the body’s ability to produce hormones and eggs. 

Symptoms of early menopause may include: 

• Hot flushes 
• Sleep disturbances 
• Vaginal dryness 
• Mood changes 
• Reduced libido 

For younger women, the emotional impact of early menopause can be significant, particularly if they had hoped to have children in the future. Symptoms of menopause can also have a significant effect, impacting a woman’s ability to work, exercise and care for their family. 

Managing symptoms and understanding fertility implications are important parts of care. Women experiencing these effects may benefit from guidance from both oncology specialists and menopause or fertility experts. 

You can learn more in our guides on early-onset breast cancer, early menopause, and young women and breast cancer. 

Fertility and Breast Cancer Options

Several options are available to help preserve fertility before breast cancer treatment begins. These approaches are usually arranged quickly after diagnosis, before chemotherapy or other treatments start. 

Breast cancer and egg freezing

Egg freezing involves stimulating and then collecting mature eggs from the ovaries and storing them for future use. This allows women the possibility of pregnancy later, even if treatment affects ovarian function. 

Breast cancer and embryo freezing

Embryo freezing is similar to egg freezing but involves collecting and then fertilising the eggs with sperm before freezing them. This process is known as in vitro fertilization (IVF). 

This option is the most reliable and may be suitable for women who have a partner or who wish to use donor sperm. 

Ovarian tissue freezing (ovarian tissue cryopreservation)

Ovarian tissue freezing is an emerging fertility preservation technique. A small amount of ovarian tissue is removed and stored for later transplantation. The transplanted ovarian tissue is then able to produce both eggs to restore fertility, as well hormones to prevent early menopause. 

This approach is newer but still considered an option to preserve fertility and may offer hope for some women. 

Ovarian suppression during chemotherapy 

Medications can sometimes be used during chemotherapy to temporarily suppress ovarian activity, which may reduce the risk of treatment-related infertility. 

The POEMS clinical trial conducted by Breast Cancer Trials, helped demonstrate the potential benefit of this approach. 

Timing and specialist referral 

Fertility preservation treatments usually need to be completed before chemotherapy begins, so early referral to a fertility specialist is important. 

In Australia, access to fertility services may be supported through Medicare and private fertility clinics, depending on the procedure. 

You can listen to our Q&A about breast cancer and fertility, moderated by Author and Journalist Annabel Crabb, here. 

Pregnancy After Breast Cancer – Is It Safe? 

Many women worry that pregnancy after breast cancer could increase the risk of recurrence.  

While individual circumstances vary, pregnancy after breast cancer does not increase the risk of cancer returning for most women. 

In many cases, survival outcomes for women who become pregnant after treatment are similar to those who do not. This is also true for patients with hormone receptor positive breast cancers and those with BRCA 1 or BRCA 2 mutations. 

Research shows that babies born to women who have previously had breast cancer generally do just as well as those born to women without a history of cancer. They experience normal growth and development, with no increased risk of birth defects, stillbirth, neonatal death or other major health problems. 

Doctors often recommend waiting around two years after treatment before trying to conceive, as this is when the breast cancer recurrence risk is typically highest. However, timing recommendations vary depending on the individual situation. 

Pausing endocrine therapy to try for pregnancy 

For some women with hormone receptor-positive breast cancer, endocrine therapy such as tamoxifen is recommended for five to ten years after treatment. This can delay plans to start or grow a family. 

The international POSITIVE clinical trial is investigating whether temporarily pausing endocrine therapy to attempt pregnancy is safe. Early results suggest that a planned interruption does not increase the short-term risk of breast cancer recurrence. However, longer-term follow-up is still underway, and any decision to pause treatment should be made in consultation with your treating team. 

Breast Cancer and Reproductive Concerns 

Even with reassuring research, many women experience anxiety about pregnancy after breast cancer. 

Common concerns include: 

• Fear of cancer recurrence 
• Concerns about hormone exposure during pregnancy 
• Emotional stress related to fertility decisions 

Oncofertility specialists and counselling services can help women navigate these complex decisions. 

Breast Cancer and IVF 

Some women require IVF (in vitro fertilisation) for infertility after breast cancer treatment. A common concern is whether IVF fertility injections could increase the risk of breast cancer developing or returning. 

IVF involves hormonal stimulation to encourage the ovaries to produce multiple eggs. Because these medications can temporarily increase oestrogen levels, some women worry about the potential link with breast cancer. 

Current research suggests that IVF does not significantly increase breast cancer risk in the general population. It appears to be safe in women with a history of breast cancer, even hormone receptor positive breast cancer. It also appears to be safe in those with inherited genetic mutations, such as BRCA1 or BRCA2. However individual risks may differ and personalised advice from specialists should always be sought when considering IVF after breast cancer. 

Consulting both a fertility specialist and an oncology team can help ensure treatment plans are safe and appropriate. Some women require multiple IVF cycles to retrieve enough eggs. Current evidence does not link repeated egg retrieval cycles with an increase in breast cancer recurrence risk. However, long-term data on this topic remains limited. 

Individualised medical advice is recommended when planning fertility treatment. 

Do repeated egg retrieval cycles increase breast cancer risk?

Current research does not show strong evidence that repeated egg retrieval cycles or fertility treatments increase the risk of developing breast cancer or of breast cancer recurring. While these treatments involve short-term rises in hormones like oestrogen, no clear long-term link with breast cancer has been established.  

If you are considering egg freezing or IVF, it’s important to speak with your oncologist and fertility specialist to understand your individual risk and options. 

Breast Cancer During Pregnancy

Although uncommon, breast cancer during pregnancy can occur. International estimates suggest it affects around 1 in 3,000 pregnancies. 

Pregnancy does not cause breast cancer. However, hormonal changes and normal breast changes during pregnancy can sometimes make diagnosis more difficult. 

For this reason, any breast lumps or unusual change should be assessed promptly, even during pregnancy. 

When breast cancer is diagnosed during pregnancy, treatment decisions are made by a multidisciplinary team, including oncologists, obstetricians and surgeons experienced in caring for pregnant patients. 

Can breast cancer during pregnancy affect the baby?

Breast cancer itself does not spread to the baby and many treatments can still be safely given during pregnancy with careful monitoring. 

For example: 

• Surgery is generally safe during pregnancy 
• Chemotherapy may be possible during the second and third trimesters 
• Radiotherapy and hormone therapy are usually delayed until after birth 

Close monitoring throughout pregnancy helps ensure both maternal and foetal health. 

Treatment Options for Breast Cancer During Pregnancy 

Breast cancer treatment during pregnancy requires careful planning to balance effective cancer treatment with the safety of the developing baby. 

• Surgery – Breast surgery is generally considered safe during all stages of pregnancy but is ideally performed after the first trimester. Procedures may include lumpectomy or mastectomy depending on the cancer type and stage.
• Chemotherapy – Chemotherapy is usually avoided during the first trimester, when the baby’s organs are forming. However, chemotherapy may be safely given during the second and third trimesters under specialist supervision. For more information on chemotherapy during pregnancy, view our dedicated article. 
• Radiotherapy during pregnancy – Radiotherapy is typically postponed until after delivery because radiation exposure may harm the developing baby.
• Endocrine therapy and pregnancy – Hormone therapies used to treat hormone-receptor-positive breast cancer are not recommended during pregnancy and are usually started after birth. Targeted therapy during pregnancy – Many targeted therapies are also avoided during pregnancy due to potential risks to the baby. Treatment decisions are always tailored to the individual situation. 

Birth Control After Breast Cancer Treatment

Women who have completed breast cancer treatment may still need reliable contraception, particularly while taking endocrine therapy. 

For women with hormone receptor-positive breast cancer, as well as those with HER2-positive or triple negative breast cancer, hormone-based contraceptives are generally avoided. These contraceptives contain oestrogen or progesterone, which may not be suitable after breast cancer treatment. Your healthcare team can recommend the most appropriate contraception option based on your individual circumstances. 

Non-hormonal options may be recommended, such as: 

• Copper intrauterine device (IUD) 
• Condoms or barrier methods 
• Fertility awareness methods in some cases 

Choosing the right contraception method should always involve discussion with a healthcare professional. 

Breast Cancer Research and Fertility in Australia

Research continues to improve fertility options for women diagnosed with breast cancer. 

Australian researchers and organisations such as Breast Cancer Trials are contributing to important studies on: 

• Fertility preservation techniques 
• Ovarian protection during chemotherapy 
• IVF safety after breast cancer 
• Hormone exposure and recurrence risk 

Clinical trials such as POEMS have already helped improve fertility outcomes for many women. 

Women interested in advancing research may consider discussing clinical trial participation with their healthcare team. 

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