How is the pregnancy due date calculated?

Most obstetricians use Naegele's Rule: add 280 days (40 weeks) to the first day of your last menstrual period (LMP). Our calculator adjusts that by your cycle length — if your cycle is longer than 28 days, ovulation happens later, so the due date shifts accordingly.

How accurate is a due date calculator?

When the LMP is known, the estimated due date is typically accurate within ±7 days. Only about 5% of babies are actually born on the calculated date. A first-trimester ultrasound (between 8 and 13 weeks) gives the most precise dating.

What if my cycle is irregular?

For irregular cycles, we add the difference between your cycle length and the standard 28 days. For example, with a 32-day cycle, we add 4 extra days. If your cycles are highly irregular, an early dating ultrasound at Vinayaka Hospital is the most reliable option.

Can I calculate my due date from the conception date?

Yes. If you know the conception date (often the ovulation day), the estimated due date is conception + 266 days. Choose 'Conception Date' in the calculator and we'll handle the math for you.

How do I find my pregnancy week?

Pregnancy week = (Today − LMP) ÷ 7. So if your LMP was 10 weeks ago, you're 10 weeks pregnant — even though conception happened around 8 weeks ago. This is the convention used by every obstetric guideline worldwide.

When does each trimester start and end?

First trimester: week 1 to 12. Second trimester: week 13 to 27. Third trimester: week 28 to 40. Babies born between 37 and 42 weeks are considered full-term.

Is a 9-month or 10-month pregnancy correct?

Pregnancy is roughly 9 calendar months, but obstetrically it's 40 weeks (or 10 lunar months of 28 days each). Both are correct — they just measure time differently.

When should I book my first appointment at Vinayaka Hospital?

Ideally between week 6 and week 8. We perform a dating ultrasound, confirm viability and start your antenatal care plan. You can book online, call +91 99809 55836 or WhatsApp us anytime.

Does Vinayaka Hospital offer painless delivery?

Yes. We offer 24×7 epidural analgesia, water birth and natural birthing rooms with experienced obstetricians and anaesthetists on-site at our BTM 4th Stage facility.

Will the calculator store my personal data?

No. All calculations run locally in your browser. We do not store, transmit or sell your information — your privacy is paramount.

Can You Get Pregnant on Your Period? A Gynaecologist Explains | Vinayaka Hospital, Bengaluru

"You can't get pregnant on your period" is one of the most widely repeated statements in reproductive health, and one of the least reliable. The honest answer is more useful: it is unlikely, but possible — and understanding why helps whether you are trying to conceive or trying to avoid pregnancy.

The Short Answer

The chance of pregnancy from sex during your period is lower than at other points in your cycle, but it is not zero. Period days are generally the lowest-risk time, not a risk-free one.

Why It Can Happen: Two Biological Facts

1. Sperm can outlast your period. Sperm can survive in the female reproductive tract for up to about five days under favourable conditions. An egg, by contrast, survives only around 12 to 24 hours after ovulation. Pregnancy happens when living sperm are already waiting when the egg is released.

2. Ovulation does not always happen on "day 14". Day 14 is an average for a 28-day cycle, not a rule. Ovulation typically occurs about 12 to 14 days before your next period, so the shorter your cycle, the earlier you ovulate. Some studies suggest only around 30% of women are actually in their fertile window between days 10 and 17 of their cycle.

A Worked Example

Say your cycle is 24 days and your period lasts six days:

Ovulation is likely around day 10 (24 minus 14)
You have unprotected sex on day 6, the last day of bleeding
Sperm can survive until about day 11, so they may still be present when the egg is released

That is a realistic route to pregnancy, entirely during or right after a period.

Who Has a Higher Chance?

People with shorter cycles (around 21 to 24 days)
People with longer periods (7 days or more), which bring sex closer to the fertile window
People with irregular cycles, where ovulation timing is hard to predict
People whose cycles have recently changed — for example after weight change, stress, new medication, childbirth, breastfeeding, or during perimenopause
Anyone who mistakes ovulation bleeding or breakthrough spotting for a period

"Safe Days" and Calendar Methods

There is no reliable "safe day" you can work out from calendar maths alone. Even regular cycles fluctuate month to month. Fertility-awareness methods can work for some couples, but they require careful daily tracking and carry a higher failure rate than dependable contraception.

If You're Trying to Conceive

Period sex is unlikely to be the reason you are not conceiving, and it also is not your best-timed opportunity. The most fertile days are the few days leading up to and including ovulation. If you have been trying for a year without success (or six months if you are 35 or older), it is reasonable to seek a fertility evaluation.

If You're Trying to Avoid Pregnancy

Use a contraceptive method consistently, including during your period
Condoms also protect against sexually transmitted infections, which period sex does not prevent
If you have had unprotected sex and want to avoid pregnancy, emergency contraception is available, and it works best the sooner it is taken. Speak to a doctor or pharmacist promptly

When to See a Gynaecologist

Your cycles are very short, very long, or unpredictable
You are unsure whether bleeding is a true period or mid-cycle spotting
You would like help choosing a contraceptive that suits your body and lifestyle
You are having trouble conceiving
You have missed a period after unprotected sex

Frequently Asked Questions

Can I get pregnant on the first day of my period?

It is the least likely time, but not impossible, particularly with a very short cycle or if the bleeding is not actually a true period.

Can I get pregnant right after my period ends?

Yes. If you ovulate early, sperm from sex in the last days of your period, or just after, can still be alive when the egg is released.

Does period blood wash sperm away?

No. Sperm travel quickly past the vagina into the cervix and uterus, so blood does not reliably prevent pregnancy.

Is bleeding in early pregnancy possible?

Light bleeding can occur in early pregnancy and is sometimes mistaken for a period. If your "period" is unusually light or short, or you have other pregnancy symptoms, a pregnancy test is worth taking.

Are there "safe days" if my cycle is very regular?

Regular cycles reduce unpredictability but do not eliminate it. Stress, illness, travel, and hormonal shifts can move ovulation without warning.

A Note From Vinayaka Hospital

Understanding your own cycle is the foundation of both planning and preventing pregnancy. At Vinayaka Hospital, Bengaluru, we offer personalised, patient-first contraception counselling and fertility guidance built around your cycle and your goals — without judgement and without one-size-fits-all rules.

Dr. Jaya Subrahmanyam
Senior Gynaecologist & Obstetrician
25+ Years of Experience

Vinayaka Hospital
429/51/1-1, Vishweshwaraiah Road, 80 Feet Road, Opp. Indian Oil Petrol Bunk, Devarachikkanahalli
BTM 4th Stage, Bengaluru – 560076

Can You Get Pregnant on Your Period? The Real Answer