Your Cycle, Timing and Contraception

Count the cycle from the first day of bleeding as day 1. The first half, while a follicle matures, varies in length between people and from month to month. After ovulation, the luteal phase before the next period is fairly constant at about 14 days. So ovulation falls roughly 14 days before the next period: around day 14 in a 28-day cycle, around day 21 in a 35-day cycle. The Japan Society of Obstetrics and Gynecology defines a normal cycle as 25 to 38 days, varying by no more than 6 days from cycle to cycle.

Pregnancy is possible during roughly six days: the five days before ovulation and the day of ovulation itself. Sperm can live up to about five days inside the body, and an egg can be fertilised for about 12 to 24 hours after ovulation. The chance is highest from two days before ovulation to the day itself.

There are three signs:

1. Cervical mucus becomes clear and stretchy, like raw egg white.
2. An ovulation (LH) test turns positive; ovulation usually follows within about 24 to 36 hours.
3. Basal body temperature rises after ovulation. It confirms that ovulation happened, but by then the fertile window has mostly passed.

There is no guaranteed safe day for ejaculating inside the vagina without contraception. Ovulation can shift even in regular cycles, and a large study found that the timing of the fertile window is hard to predict even for women whose cycles are usually regular. Methods that rely on dates alone see up to about one woman in four become pregnant within a year of typical use. Bleeding that looks like a period can also be mid-cycle bleeding around ovulation.

If you want to avoid pregnancy, use a reliable method such as the pill or a hormonal IUS. Only condoms protect against sexually transmitted infections. If contraception fails, emergency contraception works within 72 hours, and the sooner the better. Since February 2026 it has been available in Japan at a pharmacy without a prescription (a pharmacist must explain it to you in person).

1. Have sex every one to two days through the fertile window. It works better than betting everything on guessing the exact day.
2. Don't wait for your temperature to rise; by then it is mostly too late.
3. Start before, using mucus and ovulation tests as your guide.
4. Some lubricants slow sperm; if you need one, choose a fertility-friendly type.
5. Once you start planning a pregnancy, take 400 micrograms of folic acid a day as a supplement (the Japanese Ministry of Health recommendation).
6. If you are under 35 and not pregnant after a year of trying, or 35 or over after six months, see a doctor together.

If your cycle falls outside 25 to 38 days, varies by more than six days, or stops for three months or more, see a gynaecologist, and take a pregnancy test first.

Common causes: stress, sudden weight change, not eating enough, intense exercise, disrupted sleep, polycystic ovary syndrome, thyroid disease, raised prolactin, breastfeeding, and the transition towards menopause.

To bring it back:

1. Find the cause: blood tests and an ultrasound show what is happening.
2. Work on the cause: restore the balance of food and weight, sleep and exercise; treat any condition found.
3. The pill can make bleeding regular again. It creates a rhythm of bleeding rather than curing the underlying cause; chosen knowingly, it is a good option.
4. Kampo medicines (such as tokishakuyakusan) are sometimes used; as traditional prescriptions, discuss them with a doctor.

In Japan the low-dose pill needs a doctor's prescription (online consultations exist). The detailed rules differ between products, so follow your leaflet. The basics:

1. Starting: start on day 1 of your period and you are protected from that day. Start on any other day and use condoms as well for the first seven days.
2. Every day at the same time: use an alarm. With 21-tablet packs take a 7-day break; with 28-tablet packs carry on through the placebo tablets.
3. A missed pill: take it as soon as you remember, then the next at your usual time (two in one day is fine). If you miss two or more, use condoms for seven days, and consider emergency contraception if you had sex without protection in the days before.
4. Vomiting within 3 to 4 hours of a pill, or severe diarrhoea: treat it as a missed pill.
5. Interactions: some anti-epilepsy drugs, the tuberculosis drug rifampicin, and St John's wort weaken it.
6. Who shouldn't take it: smokers aged 35 or over, people with migraine with aura, a history of blood clots, and some other conditions; the doctor will check.
7. Warning signs: severe abdominal pain, chest pain, a severe headache, changes in vision, strong pain or swelling in one leg. Get care straight away.

Spotting and nausea in the first three months usually settle. The pill does not protect against sexually transmitted infections.

No method is effortless, certain and gentle all at once. The table sets out effectiveness, effort, cost, body burden and invasiveness side by side. Costs are approximate and vary between clinics. Many methods widely used abroad, such as the implant, the injection, the patch and the ring, are not approved in Japan.

Questions for choosing:

1. How important is avoiding pregnancy to me right now?
2. Can I make it a daily habit, or do I want something I can put in and forget?
3. Am I comfortable using hormones?
4. Do I need protection from STIs? (If so, add condoms.)
5. Do I also have painful or heavy periods? (The pill and the hormonal IUS often ease them.)