From the Guidelines
The chances of a girl getting pregnant one day after her period stops are low, but can be increased with vaginal intercourse every 1–2 days beginning soon after the menstrual period ends. This is because the 6-day interval ending on the day of ovulation is the most fertile period, characterized by slippery, stretchy cervical mucus and other possible signs of ovulation 1. Women with regular menstrual cycles can increase their likelihood of becoming pregnant by having vaginal intercourse during this time. However, it's essential to note that fertility rates can be affected by factors such as being very thin or obese, consuming high levels of caffeine, smoking, consuming alcohol, using recreational drugs, and using most commercially available vaginal lubricants 1. Some key points to consider include:
- The client should be educated about peak days and signs of fertility, including the 6-day interval ending on the day of ovulation 1
- Methods or devices designed to determine or predict the time of ovulation, such as over-the-counter ovulation kits or digital telephone applications, can be discussed to help maximize fertility 1
- Understanding personal cycle through tracking basal body temperature or using ovulation predictor kits can provide more personalized information about fertility windows. If preventing pregnancy is the goal, using reliable contraception methods such as condoms, hormonal birth control, or IUDs is strongly recommended rather than relying on calendar-based predictions.
From the Research
Chances of Pregnancy After Period
- The chances of a girl getting pregnant 1 day after her period stops depend on various factors, including the length of her menstrual cycle and the timing of ovulation 2.
- Research suggests that ovulation can occur as early as 6-10 days after the start of menstruation, but this can vary from woman to woman 3.
- A study on levonorgestrel emergency contraception found that it inhibits ovulation to prevent fertilization, but its effectiveness in preventing pregnancy after ovulation is still debated 2.
- Another study on oral contraceptives found that the Pearl Index (pregnancies per 100 woman-years of use) was 0.76, indicating a low risk of pregnancy with proper use 4.
Factors Affecting Fertility
- The likelihood of pregnancy after period depends on the individual's fertility and the timing of intercourse in relation to ovulation 5.
- A review of studies on levonorgestrel emergency contraception found no evidence that it affects implantation or fertility in subsequent cycles 2.
- However, the same review noted that the evidence for an association between levonorgestrel emergency contraception and reduced fallopian tube motility or ectopic pregnancy was conflicting 2.
Bleeding Patterns and Cycle Control
- Research on oral contraceptives has shown that they can affect bleeding patterns and cycle control, with some regimens resulting in fewer bleeding days or lighter bleeding 4, 5.
- A study on a continuous regimen of levonorgestrel/ethinyl estradiol found that it continuously inhibited menses and decreased the number of bleeding and spotting days over time 3.