Supporting you, Campaigning for all
• Campaigning for better births for all
• Protecting human rights in childbirth
• Independent information about pregnancy and birth
• Raising awareness of research

For a better birth

Latest Content

Journal

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An interview with Sarah Odling Smee

AIMS Journal, 2025, Vol 37, No 1 Interview by Leslie Altic What first attracted you to being a midwife, tell us a bit about your journey and how you got to where you are…

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Birth Activists Briefing: The lates…

AIMS Journal, 2025, Vol 37, No 1 By the AIMS Campaigns Team In this article we will summarise some of the key points of data about the maternity services that have been p…

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AIMS Physiology-Informed Maternity…

AIMS Journal, 2025, Vol 37, No 1 Art by Sophie Jenna Latest update from the PIMS team! The NIHR (National Institute for Health and Care Research) recently asked the Campa…

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Events

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AIMS Workshop: Politics and power i…

This is an invitation to anyone who was ever born... ... to explore our understanding and learn together. It’s part of a short series of interactive discussions around ho…

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The 10th Annual Birth Trauma Summit

Join us online via livestream or in person at Conway Hall for a day of inspiring speakers and workshops. We promise to hold courageous conversations which challenge narra…

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Midlands Maternity & Midwifery Fest…

The Maternity and Midwifery Festivals are back face to face and we’re looking forward to meeting you in 2025. Nine events across the UK and Ireland – all of them free of…

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Latest Campaigns

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AIMS Letter to Professor Mary Renfr…

AIMS has written to Professor Mary Renfrew to thank her for taking the lead on reviewing maternity services in Northern Ireland. Her report is the first of its kind to ta…

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MBRRACE-UK Saving Lives Improving M…

By the AIMS Campaigns team This note is intended to offer both a summary and AIMS commentary on the latest annual MBRRACE-UK report. MBRRACE stands for Mothers and Babies…

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PIMS Short Case Study - Optimal Cor…

Optimal cord clamping AIMS supports midwife Amanda Burleigh’s campaign for optimal cord clamping “ Wait for White ”. Optimal cord clamping is a key part of physiological…

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Pregnancy Calculator i

When's your due date?

What does your "due date" mean? How long is a normal pregnancy? How might being given a due date affect you and your baby? Enter the first day of your last period to discover when you're most likely to give birth.... and to find out more about due dates, induction and "post date" babies.
You are weeks pregnant.
Date of the first day of your last period
Adjusted cycle length

Date of the first day of your last period

The date of your last period allows an estimation of when you ovulated and conceived your baby.

A surprising number of women will have a bleed after they are pregnant, and although seeking advice from a doctor or midwife is recommended, usually this bleeding is not a problem.

Adjusted cycle length

Your menstrual cycle is counted from the first day of one period to the first day of the next. The average menstrual cycle is 28 days long, but many women will have longer or shorter cycles than this.

Ovulation usually takes place about 14 days before the next period. This means in a short cycle ovulation will be less than 14 days after your last period and with a long cycle more than 14 days after your last period. Giving the length of the cycle allows this to be taken into account in calculating your due date.

Many women have irregular cycles which make using the last day of their period less reliable for estimating due date.