Yes, many women and men have children after chemotherapy; but some drugs, especially at high doses, reduce fertility, and sometimes this effect is permanent [1, 2]. It is usually advised to prevent pregnancy during treatment and for a while afterwards, from a few months to a year depending on the drug [1, 9, 10]. In studies, pregnancy after breast cancer did not raise the risk of the cancer coming back, and the children of cancer survivors did not have more birth defects than other children [4, 6, 7].
Key points
- Pregnancy after chemotherapy is possible for many people. How much fertility is affected depends on the type and dose of the drugs, how long treatment lasts, your age and your fertility before treatment [1, 2].
- If you might want children in the future, say so before treatment starts; freezing sperm, eggs or embryos needs to be discussed before treatment [3].
- Do not get pregnant during chemotherapy. Pregnancy is possible even with irregular periods, and the drugs can harm an unborn baby, especially in the first three months of pregnancy [1, 2].
- How long should I wait? Depending on the drug, from a few months to a year after the last dose; for example, after cyclophosphamide up to a year for women and 4 months for men. Your doctor will tell you the exact time [1, 9, 10].
- Pregnancy is possible after breast cancer too: in a large study, 3 in 4 women who paused hormone therapy to try for a baby became pregnant, and the cancer did not come back more often over 5 years [5].
- The baby's health: the children of cancer survivors do not have more birth defects than other children; after breast cancer, premature birth and low birth weight have been seen slightly more often [6, 7].
Does chemotherapy cause infertility?
Sometimes, but not always. Chemotherapy can damage the ovaries and reduce the number of healthy eggs, or damage sperm. This effect is sometimes temporary and sometimes permanent [1, 2].
Several things determine the risk [1, 2]:
- Type of drug: drugs called "alkylating agents", such as cyclophosphamide, carry a higher risk [2].
- Dose and number of drugs: higher doses or several drugs together raise the risk [2].
- Age and length of treatment: your age at the time of treatment, how long treatment lasts and your fertility before the illness also matter [2].
- Other treatments: radiotherapy to the pelvis or brain and some operations also affect fertility [2].
Periods coming back does not on its own show that fertility is fully intact; sometimes the ovaries are damaged but still release an egg now and then [2]. A blood test for a hormone called AMH gives a better picture of the egg reserve. In a study of young women after breast cancer, nearly half had a very low egg reserve; this was more common in older women and in those who had had chemotherapy, and it lowered the chance of pregnancy [8].
How long after chemo can you get pregnant?
Prevent pregnancy during treatment and for a while after the last dose. How long depends on the drugs:
- Women: the US National Cancer Institute advises preventing pregnancy during chemotherapy and for a year afterwards [1]. In the official prescribing information of the drugs, this period is up to a year for cyclophosphamide and 6 months after the last dose for doxorubicin [9, 10].
- Men: chemotherapy can damage sperm [1]. Prevent your partner from becoming pregnant for 4 months after cyclophosphamide and 3 months after doxorubicin [9, 10]. Sperm collected soon after starting or finishing treatment may carry more genetic damage [3].
- Breast cancer drugs: pregnancy should be prevented for 2 months after stopping tamoxifen and for 7 months after the last dose of trastuzumab [11, 12].
These times relate only to the drugs themselves. Your doctor will tell you the right time based on the type of cancer and any treatment that is still continuing; ask: "How long should I prevent pregnancy, and when can we start trying for a baby?" [2]
Can you get pregnant during chemo?
You can become pregnant during chemotherapy, even if your periods have become irregular or occasional [2]. But chemotherapy can harm an unborn baby, especially in the first three months of pregnancy [1].
- If you still have periods, you may be asked to take a pregnancy test before treatment starts [1].
- Choose a reliable method of contraception with your doctor [1, 2]. If you take tamoxifen, the contraceptive pill and other hormonal methods may not work; use a non-hormonal method, such as condoms [11].
- If you think you might be pregnant, tell your doctor straight away so that they can talk with you about your treatment [1].
- In the first days after each dose, use condoms during sex so that your partner is not in contact with body fluids containing the drug [1]; see Is chemotherapy dangerous for the people around me?
If cancer is diagnosed during pregnancy, that is a different situation, and the treatment team will look at the options suitable for that time [1]; for doctors, see Cancer during pregnancy: chemotherapy and decisions.
Egg and sperm freezing before chemotherapy
The best time to think about having children in the future is before treatment starts. The American Society of Clinical Oncology guideline says that everyone should be counselled about the effects of treatment on fertility at diagnosis, and that those who are interested or unsure should be referred to a fertility specialist [3]:
- Men: sperm freezing before treatment. If a semen sample is not possible, sperm can be taken from the testicle in a small operation [3].
- Women: freezing eggs, embryos or ovarian tissue. Embryo freezing usually starts with hormone tests and an ultrasound scan [2, 3]. If radiotherapy to the pelvis is needed, the ovaries can be moved out of the radiation field with surgery [3].
- An injection that temporarily switches off the ovaries during chemotherapy (such as goserelin) may help women with breast cancer, but it does not replace freezing eggs or embryos [3].
- If there was no chance before treatment, eggs or embryos can sometimes be frozen after treatment [3].
In a study of young women with hormone receptor-positive breast cancer, freezing eggs or embryos before treatment did not raise the risk of the cancer coming back [5]. Read more: Fertility and sex during cancer treatment.
Having a baby after breast cancer
Many young women worry that pregnancy hormones could bring breast cancer back. Studies have not borne out this worry:
- A large review of 39 studies: women who became pregnant after breast cancer did not have the cancer come back more often than women who did not become pregnant, and they even did better; this did not depend on the timing of the pregnancy or the type of tumour [6].
- A study of 516 women aged 42 or younger with hormone receptor-positive breast cancer: after 18 to 30 months of hormone therapy, they paused it to try for a baby. In the first 3 years, the cancer did not come back more often than in similar women who had not stopped treatment [4].
- 5-year follow-up of the same study: the cancer came back about equally often in both groups. 3 in 4 women became pregnant, and about 7 in 10 had at least one baby [5]. Follow-up continues for longer, because hormone receptor-positive breast cancer can come back many years later [5].
After breast cancer, the chance of pregnancy is less than half that of other women [6]; if you want a child, talk to a fertility specialist early. Make decisions about when to try for a pregnancy and about pausing hormone therapy with your oncologist [4].
Is the baby at risk after chemotherapy?
In a large study of more than 4,000 children of people who had cancer in childhood, birth defects were no more common in children whose mother or father had had alkylating chemotherapy drugs (such as cyclophosphamide) or radiotherapy than in the children of survivors who had not had these treatments [7]. A large review of pregnancies after breast cancer also found no more birth defects [6].
However, after breast cancer, especially after chemotherapy, premature birth, low birth weight and caesarean section have been seen slightly more often [6]. Tell your obstetrician what treatments you have had so that the pregnancy can be followed closely.
Frequently asked questions
What is the chance of getting pregnant after chemo?
It is different for everyone and depends on the drugs, the dose and your age [2]. After breast cancer, the overall chance of pregnancy is less than half that of other women [6]. But among young women who deliberately tried for a baby, 3 in 4 became pregnant [5]. An AMH test helps the doctor estimate your chances more accurately [8].
My periods have come back after chemo; does that mean my fertility is normal?
What are the risks of getting pregnant during chemo?
My partner has had chemotherapy; how long should we wait?
Prevent pregnancy during treatment and for a few months after the last dose; for example, 4 months after cyclophosphamide and 3 months after doxorubicin [1, 9, 10]. Sperm may carry more genetic damage soon after treatment; ask your partner's doctor about the exact timing [3].
When should I talk about freezing eggs or sperm?
Does a goserelin injection during chemotherapy protect fertility?
For women with breast cancer, this injection, which temporarily switches off the ovaries, can be offered as an extra measure, but it does not replace freezing eggs or embryos [3]. Read more: Goserelin (Zoladex).
Can you have a baby after lymphoma or leukaemia?
Yes, it is possible. Many cancer survivors, including people who had cancer in childhood, go on to have children; in a study of more than 4,000 of their children, a parent's chemotherapy or radiotherapy had not raised the risk of birth defects [7]. Because some of the drugs used for these illnesses, such as cyclophosphamide, affect fertility more, ask about fertility preservation before treatment [2, 3].
Evidence and recommendations (for physicians)
For physicians
ASCO 2025 (fertility preservation). Assess and counsel on reproductive risks at diagnosis and during survivorship; refer interested or uncertain patients to reproductive specialists before treatment. Males: sperm cryopreservation before treatment, with TESE if unable to provide a semen sample; advise of potentially higher genetic damage risks in sperm collected soon after therapy initiation and completion. Females: embryo, oocyte and ovarian tissue cryopreservation, ovarian transposition and conservative gynaecological surgery; IVM as an emerging method; post-treatment FP for those who did not undergo pretreatment FP. GnRHa should not replace established methods but may be offered as an adjunct in breast cancer [3].
POSITIVE (NEJM 2023). 516 women aged 42 or younger, stage I to III (93.4% stage I or II), after 18 to 30 months of adjuvant endocrine therapy; median age 37 years and median 29 months from diagnosis to enrolment. Of 497 women followed for pregnancy status, 368 (74.0%) had at least one pregnancy and 317 (63.8%) at least one live birth (365 babies). At 1,638 patient-years (median follow-up 41 months), 44 breast cancer events occurred, below the safety threshold (46 events); 3-year incidence 8.9% (6.3 to 11.6) vs 9.2% (7.6 to 10.8) in the external control cohort [4].
POSITIVE update (Ann Oncol 2026). Interruption after 18 to 30 months and for up to 2 years; 518 women. At a median follow-up of 71 months, 5-year cumulative incidence of BCFI events 12.3% vs 13.2% in SOFT/TEXT controls (difference −0.9%; 95% CI −4.2% to 2.6%) and DRFI 6.2% vs 8.3%. 377 of 497 (76%) had a pregnancy and 343 (69%) a live birth, 440 offspring in total. 180 women (36%) had pre-enrolment embryo/oocyte cryopreservation; 5-year BCFI 14.0% vs 11.5% (unadjusted analysis) [5].
Hormonal factors in POSITIVE (Breast 2025). AMH below 0.5 ng/mL at month 3 after interruption in 209 of 438 women (47.7%), more frequent at older age and after chemotherapy; low reserve was associated with lower odds of pregnancy (OR 0.52; 0.31 to 0.87). Premature ovarian insufficiency (FSH above 25 IU/L at month 12) in 16.7% of those who had received chemotherapy [8].
Lambertini 2021 (meta-analysis, JCO). 39 studies; 112,840 patients with breast cancer, of whom 7,505 became pregnant after diagnosis. Likelihood of pregnancy vs the general population RR 0.40 (0.32 to 0.49); higher risk of caesarean section (OR 1.14), low birth weight (1.50), preterm birth (1.45) and small for gestational age (1.16), particularly after chemotherapy; no significant increase in congenital anomalies. Compared with patients without pregnancy: DFS HR 0.66 (0.49 to 0.89) and OS HR 0.56 (0.45 to 0.68), irrespective of the timing of pregnancy [6].
Signorello 2012 (CCSS). 4,699 children of 1,128 male and 1,627 female survivors of childhood cancer; prevalence of anomalies 2.7%. Mothers exposed to radiation or alkylating agents vs neither 3.0% vs 3.5% (P=0.51), and fathers 1.9% vs 1.7% (P=0.79); ovarian or testicular radiation dose and alkylating agent treatment were not significantly associated with anomalies [7].
| Drug | Female patients | Male patients (with female partners of reproductive potential) |
|---|---|---|
| Cyclophosphamide | During treatment and for up to 1 year after completion of therapy [9] | During treatment and for 4 months after completion of therapy [9] |
| Doxorubicin | During treatment and for 6 months afterwards [10] | During treatment and for 3 months afterwards [10] |
| Trastuzumab | During treatment and for 7 months after the last dose; exposure during pregnancy or within 7 months before conception can cause fetal harm [12] | Not stated in the label [12] |
| Tamoxifen | While taking it and for 2 months after stopping; barrier or non-hormonal methods [11] | Not stated in the label [11] |
The NCI advises women to prevent pregnancy during chemotherapy and for a year afterwards [1].
Related cancer types
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References
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