Cancer in Pregnancy: SMFM Releases First Dedicated Guidance for Surgery and Chemotherapy Timing

Cancer in pregnancy management now has dedicated guidance from the Society for Maternal-Fetal Medicine, with 14 evidence-graded recommendations covering imaging, surgery at any gestational age, chemotherapy after 12 weeks, and delivery planning. SMFM Consult Series #76 was endorsed by ACOG and published in March 2026.

April 26, 2026 · 4 min read

The Story at a Glance:

Cancer in pregnancy now has its first dedicated SMFM Consult Series, recommending surgery at any gestational age and chemotherapy generally after 12 weeks
Approximately 1 in 1,000 pregnancies is complicated by cancer, and incidence is rising in reproductive-age people
Planned delivery before 37 weeks should generally be avoided unless medically or obstetrically indicated
Most chemotherapy agents are stopped after 34 weeks, and delivery is planned 3–4 weeks after the last cycle

What Happened

Cancer in pregnancy now has its first dedicated SMFM Consult Series. The Society for Maternal-Fetal Medicine published Consult Series #76 in Pregnancy in March 2026, endorsed by ACOG. The document distills 14 evidence-graded recommendations covering imaging, surgery, systemic therapy, thromboprophylaxis, fetal surveillance, and delivery timing.

The lead author is Moti Gulersen, MD, MSc, of Sidney Kimmel Medical College at Thomas Jefferson University, with co-authors from the SMFM Publications Committee. The guidance covers breast, cervical, colorectal, Hodgkin lymphoma, leukemia, melanoma, non-Hodgkin lymphoma, ovarian, and thyroid cancers — the malignancies most often encountered in pregnant patients. The headline message is that cancer treatment should not be withheld based on pregnancy status alone, while balancing maternal benefit against fetal risk and the patient’s reproductive goals.

Why Cancer in Pregnancy Now Has Dedicated Guidance

Cancer affects roughly 1 in 1,000 pregnancies, and the incidence of cancer in U.S. reproductive-age people has risen since 2010, disproportionately among females. Expanded use of cell-free DNA (cfDNA) prenatal screening has also led to incidental detection of preclinical and metastatic maternal cancers — a route to diagnosis that did not exist a decade ago.

Until now, U.S. obstetricians have managed these patients using case reports, registry data, and oncology-led documents. SMFM Consult Series #76 is the first SMFM-led, ACOG-endorsed source that consolidates the evidence in one place and grades each recommendation.

Key Numbers Behind the Cancer in Pregnancy Update

Several figures underpin the practical thresholds in the new guidance.

~1 in 1,000 pregnancies complicated by cancer
12 weeks — gestational age after which chemotherapy is generally administered, allowing organogenesis to complete
OR 3.9 (95% CI, 1.4–10.9) — increased odds of spontaneous preterm birth before 37 weeks when chemotherapy starts before 18 weeks (cohort of 225 pregnancies)
OR 2.3 (95% CI, 1.0–4.9) — increased risk of fetal growth restriction (FGR) when chemotherapy starts before 15 weeks
34 weeks — gestational age after which most chemotherapy agents are discontinued
3–4 weeks — recommended interval between the last chemotherapy cycle and delivery, allowing maternal and neonatal myelosuppression to resolve
≥37 weeks — minimum target for planned delivery in the absence of a medical or obstetric indication for earlier birth (GRADE 1C)
Every 3–4 weeks — frequency of fetal growth surveillance during active cancer treatment

What Experts Are Saying

“Cancer treatment should not be withheld based on pregnancy status alone.” — SMFM Consult Series #76: Cancer in Pregnancy, headline recommendation

Lead author Moti Gulersen, MD, MSc, framed the document as overdue, noting that clinicians have been managing pregnant patients with cancer without consolidated guidance and that advances in oncology and multidisciplinary care now allow many patients to receive treatment safely during pregnancy.

An independent perspective comes from the American Society of Clinical Oncology, which released its own clinical practice guideline on management of cancer during pregnancy in December 2025. Side-by-side analyses from Guideline Central show broad alignment with SMFM on surgery at any gestational age, chemotherapy timing after 12–14 weeks, and avoidance of routine preterm delivery — with some nuance on intraoperative positioning, anesthesia choice, and postpartum thromboprophylaxis duration.

What’s Next

The Consult Series will inform institutional protocols, EHR templates, and joint care pathways with oncology, neonatology, and anesthesia services over the coming months. SMFM has released an accompanying podcast featuring Drs. Clarissa Bonanno and Elyce Cardonick, and patient-facing resources are being added through the SMFM and HOPE for TWO networks.

Expect society-level harmonization with the December 2025 ASCO guideline, additional joint statements with surgical and anesthesia societies, and updated quality measures targeting timely multidisciplinary consultation after a cancer diagnosis in pregnancy.

Bottom Line

Assemble a multidisciplinary team at diagnosis — maternal-fetal medicine, oncology, general OB, neonatology, anesthesia, and psychology — for any pregnant patient with cancer in pregnancy
Do not delay or withhold surgery based on gestational age; coordinate timing and positioning with oncology and anesthesia
Defer chemotherapy until after 12 weeks when prognosis allows; counsel about preterm-birth and FGR risks if treatment starts earlier
Stop chemotherapy by ~34 weeks and plan delivery at least 3–4 weeks after the last cycle
Aim for delivery at ≥37 weeks unless a medical or obstetric indication mandates earlier birth — and prefer vaginal delivery when feasible
Initiate thromboprophylaxis for active hematologic or gynecologic cancers; assess case-by-case for other tumor types
Schedule serial fetal growth scans every 3–4 weeks throughout the cancer course, regardless of treatment modality

Sources

Society for Maternal-Fetal Medicine; Gulersen M, Bonanno C, Brandt JS, Pierce S, Cardonick EH; SMFM Publications Committee. Society for Maternal-Fetal Medicine Consult Series #76: Cancer in Pregnancy. Pregnancy. 2026;2:e70221. SMFM Consult Series #76 — full text in Pregnancy (Wiley)
Society for Maternal-Fetal Medicine. SMFM Issues New Clinical Guidance for Cancer Diagnosis and Treatment During Pregnancy. SMFM news release, March 16, 2026. SMFM news release on Consult Series #76
The ASCO Post. SMFM Issues New Clinical Guidance for Cancer Diagnosis and Treatment During Pregnancy. ASCO Post, March 19, 2026. ASCO Post coverage of the SMFM cancer-in-pregnancy guidance
Guideline Central. Comparing Current SMFM and ASCO Cancer During Pregnancy Guidance. Guideline Central, April 2026. Guideline Central side-by-side comparison of SMFM and ASCO recommendations
Society for Maternal-Fetal Medicine. SMFM Publications and Clinical Guidelines. SMFM Publications Committee, 2026. SMFM Publications Committee landing page for Consult Series #76
EurekAlert. SMFM issues new clinical guidance for cancer diagnosis and treatment during pregnancy. EurekAlert, March 17, 2026. EurekAlert announcement of the SMFM cancer-in-pregnancy guidance