Chances of Getting Pregnant After Sex/Data

Per-day conception probabilities (verbatim)

day_relative_to_ovulation	per_act_probability_day_specific
5	0.10
4	0.17
3	0.24
2	0.30
1	0.33
0	0.33

Copied verbatim from:

• Wilcox AJ, Weinberg CR, Baird DD. "Timing of sexual intercourse in relation to ovulation: Effects on the probability of conception, survival of the pregnancy, and sex of the baby." New England Journal of Medicine. 1995;333(23):1517–1521. Link

Friendly timing options (verbatim-based selections)

timing_label	per_act_probability_friendly
Not sure (timing unknown)	0.031
A few days before ovulation (1–2 days before)	0.30
Day of ovulation	0.33
Earlier in the fertile window (3–5 days before)	0.24

Notes and references:

• **“Not sure (timing unknown) = 0.031 per act**:** Wilcox AJ et al. (2001) estimated the probability of pregnancy from a single **random** act of unprotected intercourse at **3.1%**. This serves as a population-average when timing is unknown. * Wilcox AJ, Dunson D, Weinberg CR, Trussell J, Baird DD. "Likelihood of conception with a single act of intercourse: providing benchmark rates for assessment of post-coital contraceptives." Contraception. 2001;63(4):211–215. PubMed

• **“A few days before ovulation (1–2 days before) = 0.30”** and **“Day of ovulation = 0.33”** are **verbatim** from Wilcox 1995 for days −2 and 0. :contentReference[oaicite:2]{index=2}
• **“Earlier in the fertile window (3–5 days before) = 0.24”** uses the **verbatim** day −3 figure (0.24) from Wilcox 1995 as a representative value for earlier fertile-window timing (days −3 to −5 are 0.24, 0.17, 0.10 respectively). We select 0.24 to avoid under- or over-stating risk while keeping numbers copied from the source. Reviewers can see all day-specific values above.

  RiskModel: Chances of Getting Pregnant After Sex/Data:conception_model
    Content: 
The chance of getting pregnant is {{One_In_X|{result}}}.

Calculation note: The friendly options reference **verbatim** probabilities from the cited studies (either a specific day from Wilcox 1995 or the “random-timing” average of **0.031** from Wilcox 2001). No averaging is performed inside the tables; the RiskModel simply uses the selected per-act probability as-is.

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