Home-based monitoring of ovulation to time frozen embryo transfers in the Netherlands (Antarctica-2): an open-label, nationwide, randomised, non-inferiority trial

Tjitske Zaat, Jan Peter de Bruin, Mariëtte Goddijn, Marchien van Baal, Sofie Benneheij, Monique Brandes, Frank Broekmans, Astrid Cantineau, Ben Cohlen, Jeroen van Disseldorp, Susanne Gielen, Eva Groenewoud, Arne van Heusden, Eugenie Kaaijk, Carolien Koks, Corry de Koning, Nicole Klijn, Paul van der Linden, Petra Manger, Lobke MoolenaarRobbert van Oppenraaij, Quirine Pieterse, Jesper Smeenk, Jantien Visser, Madelon van Wely, Femke Mol*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

6 Citations (Scopus)



The growing field of assisted reproductive techniques, including frozen-thawed embryo transfer (FET), should lead the way to the best sustainable health care without compromising pregnancy chances. Correct timing of FET is crucial to allow implantation of the thawed embryo. Nowadays, timing based on hospital-controlled monitoring of ovulation in the natural cycle of a woman is the preferred strategy because of the assumption of favourable fertility prospects. However, home-based monitoring is a simple method to prevent patient travel and any associated environmental concerns. We compared ongoing pregnancy rates after home-based monitoring versus hospital-controlled monitoring with ovulation triggering. 


This open-label, multicentre, randomised, non-inferiority trial was undertaken in 23 hospitals and clinics in the Netherlands. Women aged between 18 and 44 years with a regular ovulatory menstrual cycle were randomly assigned in a 1:1 ratio via a web-based randomisation program to home-based monitoring or hospital-controlled monitoring. Those who analysed the data were masked to the groups; those collecting the data were not. All endpoints were analysed by intention to treat and per protocol. Non-inferiority was established when the lower limit of the 90% CI exceeded –4%. This study was registered at the Dutch Trial Register (Trial NL6414). 


1464 women were randomly assigned between April 10, 2018, and April 13, 2022, with 732 allocated to home-based monitoring and 732 to hospital-controlled monitoring. Ongoing pregnancy occurred in 152 (20·8%) of 732 in the home-based monitoring group and in 153 (20·9%) of 732 in the hospital-controlled monitoring group (risk ratio [RR] 0·99 [90% CI 0·81 to 1·22]; risk difference [RD] –0·14 [90% CI –3·63 to 3·36]). The per-protocol analysis confirmed non-inferiority (152 [21·0%] of 725 vs 153 [21·0%] of 727; RR 1·00 (90% CI 0·81 to 1·23); RD –0·08 [90% CI –3·60 to 3·44]). 


Home-based monitoring of ovulation is non-inferior to hospital-controlled monitoring of ovulation to time FET. 

Original languageEnglish
Pages (from-to)1347-1355
Number of pages9
JournalThe Lancet
Issue number10410
Publication statusPublished - 14 Oct 2023

Bibliographical note

Role of the funding source:
The funder of the study had no role in study design, data
collection, data analysis, data interpretation, or writing of
the report.

The Dutch Organisation for Health Research and Development.

Publisher Copyright:
© 2023 Elsevier Ltd


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