Oral Contraceptive Pills: How Pills and Saheli Work
Biology · Reproductive Health · NEET
Oral contraceptive pills (OCPs) are tablets of progestogens alone, or progestogen-estrogen together, taken daily for 21 days from the first 5 days of the cycle, then a 7-day gap. They mainly inhibit ovulation and implantation and also change cervical mucus so sperms cannot pass easily. Saheli is different: it is a NON-STEROIDAL, "once a week" pill made in India (CDRI, with ICMR support) with very few side effects. Memory hook: "Pill = daily 21+7, Saheli = weekly & steroid-free."
Regular oral pills are steroidal hormones taken daily (21+7) and inhibit ovulation and implantation, while Saheli is a non-steroidal, once-a-week pill that blocks estrogen receptors to prevent implantation.
Your doubts, answered
Do oral contraceptive pills contain hormones? Which ones?
Yes. Normal OCPs contain either progestogens alone or a progestogen-estrogen combination. These are steroid hormones. Because pills use hormones, NEET groups them with lactational amenorrhea, injectables, implants and emergency pills as HORMONAL methods. Barrier methods and copper-T (CuT) are non-hormonal.
For how many days are the pills taken?
Pills are taken DAILY for 21 days, preferably starting within the first 5 days of the menstrual cycle. Then there is a 7-day gap during which menstruation occurs. After the gap, the same 21-day pattern is repeated as long as the woman wants to prevent conception. Remember: 21 days on + 7 days gap.
How exactly do pills prevent pregnancy?
They mainly inhibit OVULATION (no egg is released). They can also inhibit IMPLANTATION and change the quality of cervical mucus so that entry of sperms is retarded. NEET match questions pair 'Contraception Pills → inhibit ovulation and implantation.'
How is Saheli different from ordinary pills?
Saheli is a NON-STEROIDAL preparation (not a hormone), while ordinary pills are steroidal hormones. Saheli is a 'once a week' pill, but ordinary pills are taken daily for 21 days. Saheli was developed by CDRI (with ICMR collaboration) and has very few side effects and high contraceptive value.
Are contraceptive pills the same as emergency contraceptives?
No. Ordinary OCPs are taken regularly to prevent pregnancy in advance. Emergency contraceptives use progestogens or progestogen-estrogen combinations (or IUDs) WITHIN 72 hours of coitus to avoid pregnancy after unprotected sex. Do not confuse the regular pill with the post-coital emergency pill.
⚠️ The NEET trap ✗ Saheli increases estrogen and prevents ovulation, or Saheli is an IUD / a post-coital pill. ✓ Saheli is a NON-STEROIDAL 'once a week' ORAL pill; it acts as an anti-estrogen and blocks estrogen receptors, preventing implantation. It is NOT an IUD and NOT an emergency (post-coital) contraceptive. 🧠 Saheli trap: students tick 'increases estrogen' or 'emergency/IUD'.
Real NEET questions
NEET 2019
Which of the following contraceptive methods do involve a role of hormone?
A · Lactational amenorrhea, Pills, Emergency contraceptives ✓
B · Barrier method, Lactational amenorrhea, Pills
C · CuT, Pills, Emergency contraceptives
D · Pills, Emergency contraceptives, Barrier methods
Solution: Lactational amenorrhea suppresses ovulation hormonally, oral pills use progestogen/estrogen, and emergency contraceptives use progestogens or progestogen-estrogen — all three are hormone-based. CuT (copper IUD) and barrier methods act physically, so options with them are wrong.
NEET 2022
Match List I (methods of contraception) with List II (their actions): (a) Diaphragms (b) Contraception Pills (c) Intrauterine Devices (d) Lactational Amenorrhea | (i) Inhibit ovulation and Implantation (ii) Increase phagocytosis of sperm within Uterus (iii) Absence of Menstrual cycle and ovulation following parturition (iv) They cover the cervix blocking the entry of sperms
A · (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
B · (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii) ✓
C · (a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
D · (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)
Solution: Diaphragms cover the cervix (iv); pills inhibit ovulation and implantation (i); IUDs increase phagocytosis of sperms in the uterus (ii); lactational amenorrhea is absence of ovulation after parturition (iii). Key link for this page: Contraception Pills → inhibit ovulation and implantation.
NEET 2018
The contraceptive 'SAHELI'
A · is an IUD
B · increases the concentration of estrogen and prevents ovulation in females
C · blocks estrogen receptors in the uterus, preventing eggs from getting implanted ✓
D · is a post-coital contraceptive
Solution: Saheli is a non-steroidal 'once a week' oral pill (centchroman) that acts as an anti-estrogen, blocking estrogen receptors in the uterus and preventing implantation. It is not an IUD and not a post-coital/emergency contraceptive, and it does not raise estrogen.
Solved Reproductive Health NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
When should a woman start taking OCPs in her cycle?
Preferably within the first 5 days of the menstrual cycle, then daily for 21 days, followed by a 7-day gap during which menstruation occurs. The 21-day cycle is then repeated.
Who developed Saheli and is it a hormone?
Saheli was developed by CDRI (Central Drug Research Institute), Lucknow, with ICMR collaboration. It is a NON-STEROIDAL preparation, so it is not a hormone-based pill, and it has very few side effects.
Do OCPs protect against STIs?
No. Oral pills prevent pregnancy but give no protection against sexually transmitted infections. Only condoms (barrier method) reduce STI risk. This distinction is often tested in NEET.
Is Saheli taken daily like ordinary pills?
No. Saheli is a 'once a week' pill, whereas ordinary OCPs are taken daily for 21 days. This day-count difference is a common NEET one-liner.
