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A revised prediction model for natural conception

Reproductive BioMedicine Online


  • The Hunault model is the standard prediction model for natural conception.
  • This model can be revised by including additional predictors.
  • The revised model is applicable to a broader population.
  • The revised model needs to be externally validated.


One of the aims in reproductive medicine is to differentiate between couples that have favourable chances of conceiving naturally and those that do not. Since the development of the prediction model of Hunault, characteristics of the subfertile population have changed. The objective of this analysis was to assess whether additional predictors can refine the Hunault model and extend its applicability.

Consecutive subfertile couples with unexplained and mild male subfertility presenting in fertility clinics were asked to participate in a prospective cohort study. We constructed a multivariable prediction model with the predictors from the Hunault model and new potential predictors. The primary outcome, natural conception leading to an ongoing pregnancy, was observed in 1053 women of the 5184 included couples (20%). All predictors of the Hunault model were selected into the revised model plus an additional seven (woman's body mass index, cycle length, basal FSH levels, tubal status,history of previous pregnancies in the current relationship (ongoing pregnancies after natural conception, fertility treatment or miscarriages), semen volume, and semen morphology. Predictions from the revised model seem to concur better with observed pregnancy rates compared with the Hunault model; c-statistic of 0.71 (95% CI 0.69 to 0.73) compared with 0.59 (95% CI 0.57 to 0.61).

Keywords: Natural conception, Prediction model, Prognosis, Subfertility.


1 Medisch Centrum Alkmaar, Alkmaar

2 Twenteborg Ziekenhuis, Almelo

3 Meander Medisch Centrum, Amersfoort

4 Academisch Medisch Centrum, Amsterdam

5 BovenIJ Ziekenhuis, Amsterdam

6 St. Lucas Adreas Ziekenhuis, Amsterdam

7 Onze Lieve Vrouwe Gasthuis, Amsterdam

8 Slotervaart Ziekenhuis, Amsterdam

9 Vrije Universiteit Medisch Centrum, Amsterdam

10 Gelre Ziekenhuis, Apeldoorn

11 Wilhelmina Ziekenhuis, Assen

12 Rode Kruis Ziekenhuis, Beverwijk

13 Ziekenhuis Gooi-Noord, Blaricum

14 Amphia Ziekenhuis Breda, Breda

15 Medisch Centrum Haaglanden, lcoatie Westeinde, Den Haag

16 Ziekenhuis Deventer, Deventer

17 A. Schweitzer Ziekenhuis, Dordrecht

18 Scheper Ziekenhuis, Emmen

19 Medisch Spectrum Twente, Enschede

20 St. Anna Ziekenhuis, Geldrop

21 Atrium Medisch Centrum, Heerlen

22 Elkerliek Ziekenhuis, Helmond

23 Jeroen Bosch Ziekenhuis, ‘s Hertogenbosch

24 Ziekenhuis Hilversum, Hilversum

25 Spaarne Ziekenhuis, Hoofddorp

26 Westfries Gasthuis, Hoorn

27 Academisch Ziekenhuis Maastricht, Maastricht

28 St. Antonius Ziekenhuis, Nieuwegein

29 UMC St. Radboud, Nijmegen

30 Waterland Ziekenhuis, Purmerend

31 St. Franciscus Gasthuis, Rotterdam

32 TweeSteden Ziekenhuis, Tilburg/Waalwijk

33 UMC Utrecht, Utrecht

34 Ziekenhuis Bernhoven, Veghel

35 Máxima Medisch Centrum, Veldhoven

36 Vie Curi Medisch Centrum, Venlo/Venray

37 Zaans Medisch Centrum, Zaandam

38 Isala Klinieken, Zwolle

a Centre for Reproductive Medicine, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands

b Centre for Reproductive Medicine, Jeroen Bosch Hospital, Henri Dunantstraat 1, 5223 GZ ‘s-Hertogenbosch, The Netherlands

c Centre for Reproductive Medicine, Sint Elisabeth Hospital, Hilvarenbeekseweg 60, 5022 GC Tilburg, The Netherlands

d Department of Public Health, Erasmus MC, University Medical Centre Rotterdam, Dr Molewaterplein 50-60, 3015 GE Rotterdam, The Netherlands

e Department of Obstetrics and Gynecology, Vrije Universiteit Medical Centre, De Boelelaan 1118, 1081 HZ Amsterdam, The Netherlands

f Department of Clinical Epidemiology and Biostatistics, Academic Medical Centre, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands

g The Robinson Institute, School of Paediatrics and Reproductive Health, University of Adelaide, Australia

h Julius Centre for Health Sciences and Primary Care, University Medical Centre Utrecht, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands

* Corresponding author.