# Pregnancy and breastfeeding checks before radiotherapy

Source: https://onco.cc/protocols/radiotherapy-pregnancy-and-breastfeeding-enquiry/  
OnCo record `radiotherapy-pregnancy-and-breastfeeding-enquiry` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Radiation can harm an unborn baby, so before your planning scan and your first treatment, anyone who could be pregnant is asked whether they might be, and before a radioactive medicine is given, whether they are breastfeeding. The answer is recorded; if pregnancy cannot be ruled out a test may be done, and if you are pregnant the team reconsiders the plan with you.

## Summary

In the UK, IR(ME)R 2017 regulation 11(1)(f) requires the operator to enquire about pregnancy where relevant, and the RCR guidance (second edition, October 2026, with UKHSA) sets out how. The employer's written procedure defines who is asked (commonly people of childbearing potential aged 12 to 55, some departments 10 to 55), when (asking before the first planning exposure and before the first treatment may be sufficient), exceptions (for example after total abdominal hysterectomy), sedated or anaesthetised patients, under-16s (local safeguarding procedure), trans and gender-diverse people, and irregular cycles, where the ten-day rule and menstrual history may not predict pregnancy and routine testing may be specified. The answer is documented; a refusal to answer is documented and the unknown-status procedure followed. If pregnancy is possible or confirmed, the practitioner reconsiders justification, deferral is considered and a test is done where it cannot be excluded. For molecular radiotherapy menstrual history alone is not adequate to exclude pregnancy, and breastfeeding is completely contraindicated where the radionuclide enters milk. Deliberately treating a pregnant patient is rare, case by case, with a prior risk assessment by the medical physics expert, and AAPM TG-36 (1995) gives the physics for estimating and shielding fetal dose; an unintended fetal exposure may be notifiable.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: pregnancy check before radiotherapy; pregnancy status enquiry; IR(ME)R pregnancy enquiry; ten-day rule; 28-day rule; breastfeeding and molecular radiotherapy; radiotherapy in pregnancy; fetal dose radiotherapy

## Connected records

- protocols: [Consent for radiotherapy: who takes it, when, and what it must cover](https://onco.cc/protocols/radiotherapy-consent/), [Fertility protection before pelvic radiotherapy: ovarian transposition, egg, embryo and sperm freezing](https://onco.cc/protocols/fertility-protection-before-pelvic-radiotherapy/), [Patient identification and pre-treatment time-out in radiotherapy](https://onco.cc/protocols/radiotherapy-patient-identification-and-time-out/), [Radiotherapy planning scan (CT simulation): positioning, skin marks and what the patient does](https://onco.cc/protocols/radiotherapy-planning-ct-simulation/)
- terms: [Cancer during pregnancy](https://onco.cc/terms/cancer-in-pregnancy/)
- ideas: [Routine pregnancy testing compared with asking, before radiotherapy](https://onco.cc/ideas/idea-pu-pregnancy-test-or-ask-before-radiotherapy/)

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