A Rare but Real Situation
A glioblastoma diagnosis is disorienting under any circumstances. When it arrives during pregnancy - or when you are in your thirties and hoping to start a family - the questions pile up fast. Can treatment wait? Will temozolomide damage eggs or sperm permanently? Is it ever safe to get pregnant again after finishing radiotherapy? These are some of the most complex questions in neuro-oncology, and there is no universal protocol. There is a growing body of case evidence, evolving clinical guidance, and specialist teams that manage exactly this intersection of cancer and reproductive life.
What the Evidence Says About GBM and Pregnancy
The standard GBM treatment sequence - surgery, then six weeks of concurrent radiation and temozolomide chemotherapy, followed by additional cycles of temozolomide - poses real risks both to a developing fetus and to future fertility. But treatment during pregnancy is possible, and you can still build a family after GBM. What matters is that you and your doctors plan care around reproductive considerations from the first week, not after the fact. A multidisciplinary team - not a single specialist - is needed to make these decisions work.
How GBM Treatment Affects Fertility
Temozolomide and Reproductive Risk
Temozolomide (TMZ) is an alkylating agent - a drug that works by attaching to and damaging DNA. Alkylating agents as a class are among the chemotherapy drugs most strongly linked to fertility loss. A published review of temozolomide's gonadotoxic potential notes that doctors don't fully understand temozolomide's full impact on human fertility yet - which is precisely why pre-treatment fertility counseling is essential rather than optional. In women, TMZ may lower egg reserves and can cause early ovarian failure in some patients. In men, animal and early human studies suggest it can harm sperm production and quality.
Temozolomide can harm a fetus if a pregnant woman takes it. Doctors avoid temozolomide throughout pregnancy, especially in the first trimester when fetal organs are forming.
Brain Radiation and the Hypothalamic-Pituitary Axis
Radiation for GBM targets the brain, not the ovaries or testes. But the brain contains the hypothalamus and pituitary gland, which send hormonal signals to the gonads. A review of management considerations for women of reproductive age with glioma notes that radiotherapy aimed at the hypothalamus and pituitary gland exceeding 45 Gy can stop the production of gonadotropins - the hormones that drive ovulation and sperm production. Cranial radiation can reduce fertility indirectly, through a hormonal pathway, even though the gonads themselves receive minimal direct dose during brain treatment.
In men, scattered radiation from cranial radiotherapy can reach the testes at low doses. A review of radiation effects on male reproductive function reports that a cumulative gonadal dose above approximately 2.5 Gy can temporarily or permanently lower sperm production. Talk to your radiation oncologist about shielding options before planning begins.
When GBM Is Diagnosed During Pregnancy
GBM diagnosed during pregnancy is rare, but published case series show it is manageable with careful multidisciplinary planning. The approach changes by trimester.
First Trimester - The Highest-Risk Window
The first 12 weeks are when fetal organs form. This is the period of greatest fetal sensitivity to both radiation and cytotoxic drugs. If you're diagnosed in the first trimester, doctors usually delay or reduce full-dose chemoradiation. Some teams use surgical resection alone to manage the tumor while deferring systemic therapy. Whether to continue the pregnancy is a deeply personal decision that you and your full medical team, a high-risk pregnancy specialist, and possibly an ethics consultant need to make together. There is no one right answer.
Second Trimester - The Safer Surgical Window
Surgery - craniotomy to remove as much tumor as safely possible - carries less risk to the fetus during the second trimester than the first. Published case series report craniotomy performed during the second trimester with normal fetal outcomes in patients with glial tumors. Fetal organs are formed, anesthesia risks are more manageable than in the first trimester, and surgical decompression can relieve neurological pressure while buying time before full chemoradiation begins after delivery.
Third Trimester - Early Delivery as a Bridge
When GBM is diagnosed at 34 weeks gestation or later, doctors typically plan early delivery - by cesarean if needed - and then start full treatment right away. A case review of recurrent GBM in a pregnant patient describes a multidisciplinary team determining the best timing for delivery based on both fetal maturity and the mother's neurological condition, with infants showing normal development at follow-up. Early delivery at 34 weeks or beyond, when the fetus has reached a viable stage, is increasingly the favored approach at specialist centers when the tumor is growing rapidly.
Fertility Preservation for Women Before Treatment Starts
If you are not currently pregnant but are of reproductive age and hope to have children in the future, you and your doctors need to discuss fertility preservation before your first chemotherapy dose or radiation session. The American Society of Clinical Oncology (ASCO) recommends that all patients of reproductive age talk with a reproductive specialist about fertility risks as early as possible - before cancer treatment starts. With GBM, the time between diagnosis and the start of treatment is short. You should get this referral within days, not weeks.
The main preservation options for women are:
- Embryo freezing (embryo cryopreservation) - Doctors retrieve your eggs after 10 to 14 days of hormone treatment, fertilize them with sperm from a partner or donor, and freeze them. This is the most established method, with the highest success rates per cycle.
- Egg freezing (oocyte cryopreservation) - Doctors collect and freeze your eggs without fertilizing them. A reasonable option if you don't have a partner or prefer to decide on fertilization later. It requires the same hormone cycle as embryo freezing.
- Ovarian tissue cryopreservation - Doctors surgically remove and freeze a portion of your ovary for possible re-implantation later. This can sometimes happen without a full hormone cycle, making it an option when treatment can't be delayed. It is an emerging method but has resulted in live births in cancer patients.
- GnRH agonist co-treatment - You take medication during chemotherapy to suppress your ovaries and potentially reduce drug damage. Evidence in GBM specifically is limited, and ASCO recommends this approach only when more established methods are not feasible.
If your neuro-oncologist has not raised fertility preservation unprompted, ask for a referral to an oncofertility specialist directly. Most large cancer centers have one in-house or can arrange a rapid consultation. Ask at your first or second appointment, before treatment planning is finalized.
Fertility Preservation for Men Before Treatment Starts
For men diagnosed with GBM, sperm banking before the first treatment is the most practical option and takes only one or two clinic visits. Even a single cycle of alkylating chemotherapy may alter sperm DNA, so you should bank sperm before your first temozolomide dose - ideally within the same week as other pre-treatment tests. Ask your oncologist or care coordinator for a direct referral to a sperm bank or andrology clinic, and ask the radiation oncologist whether the planned treatment field creates any risk of scattered dose to the testes and whether testicular shielding is possible.
Can You Have Children After GBM Treatment?
This is the question younger patients and caregivers ask most often. The honest answer: some patients have had children, but we can't predict or guarantee it, and the evidence comes from individual case reports, not large clinical trials.
Published literature includes cases of women with glioblastoma or high-grade glioma who became pregnant after completing treatment and delivered healthy children. A case report documents a patient with recurrent GBM who became pregnant after chemotherapy and delivered a healthy infant. Doctors don't yet know the long-term health outcomes for children born to parents who received alkylating agents, but published cases are reassuring, even though the studies are small.
Several things are worth knowing as you weigh this:
- There are no established clinical guidelines specifying a safe waiting period after GBM treatment before attempting pregnancy. You and your oncologist make decisions individually, case by case.
- Hormonal changes during pregnancy - particularly rising estrogen and progesterone - may interact with some brain tumors in ways doctors don't yet fully understand. This is an active area of research, and close follow-up with your neuro-oncologist during any pregnancy after treatment matters.
- The extent of your fertility risk depends partly on how aggressive your treatment needs to be - which in turn depends on your molecular markers. MGMT methylation status and IDH mutation status shape how intense your protocol will be. A plain-language explanation of these markers is in our guide to reading your glioblastoma pathology report.
The Specialist Team You Need - and Why a Second Opinion Often Changes the Plan
No single specialist can manage GBM alongside reproductive considerations alone. The core team typically includes a neuro-oncologist, a neurosurgeon, a radiation oncologist, a maternal-fetal medicine specialist (if you are currently pregnant), a reproductive endocrinologist or oncofertility specialist, and - when your doctors plan an early delivery - a neonatologist. You rarely find this combination of specialists in a single community hospital, which is why a referral to an academic brain tumor center is almost always worthwhile in these cases.
A second opinion is most likely to change your plan if you're facing this situation. If your treating center doesn't have experience managing GBM during pregnancy or doesn't have an oncofertility program, get an independent expert review before you commit to a treatment plan. You can consult the Art of Healing Cancer team on what your treatment options actually look like - a remote review of your pathology and imaging can clarify which options are genuinely available before you make irreversible decisions.
For a step-by-step guide on preparing for that kind of consultation, see our article on when a glioblastoma second opinion is likely to change your treatment plan.
If you are ready to share your case now, you can upload your MRI and reports directly through the Glioblastoma Center patient journey page to request a remote review by the team.
When to Talk to Your Doctor
Raise fertility and pregnancy considerations with your care team as soon as GBM is diagnosed - before treatment decisions are finalized. If you are currently pregnant, tell your oncologist the gestational age immediately. If you hope to have children, ask for a referral to an oncofertility specialist within the first week of diagnosis. If your oncologist has not raised these topics, you should bring them up yourself. The window for fertility preservation is short, and getting this referral won't hurt.
This article is for general information and is not a substitute for medical advice. Always consult your oncologist or care team about your specific situation.