Intended for healthcare professionals

Rapid response to:


The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study

BMJ 2000; 321 doi: (Published 18 November 2000) Cite this as: BMJ 2000;321:1259

Rapid Response:

Fitting post-coital IUCDs with a wide fertility window

Editor, The well designed paper from Wilcox et al raises some
interesting dilemmas about the timing of fitting post-coital IUCDs.

Standard advice is that an IUCD may be fitted 'in good faith' up to five
days after the calculated earliest date of ovulation. (Faculty of Family
Planning and Reproductive Healthcare 2000) Until now calculation of this
date has been based on the assumption that ovulation occurs exactly 14
days before menstruation. If it may in fact be up to 19 days before
menstruation, there is a risk of fitting an IUCD after implantation has
occurred. Perhaps the guidance needs to be reviewed in the light of this

No competing interests.

Ref: Guidance April 2000. Emergency contraception: recommendations
for clinical practice. BJFP 26(2);Apr 2000:93-96

Competing interests: No competing interests

04 January 2001
Charlotte Fleming
consultant community gynaecology
Gwent NHS Trust