Higher Hormone Interactions in the Menstrual Cycle and Contraception
Part of Contraception — GCSE Biology
This higher tier covers Higher Hormone Interactions in the Menstrual Cycle and Contraception within Contraception for GCSE Biology. Topic 9: Contraception It is section 9 of 12 in this topic. This section is most useful once the core foundation idea is secure, because it adds the detail that pushes answers higher.
Topic position
Section 9 of 12
Practice
15 questions
Recall
20 flashcards
Higher Hormone Interactions in the Menstrual Cycle and Contraception
Understanding why the pill works requires knowing the normal menstrual cycle hormone interactions. In the natural cycle: FSH (pituitary) stimulates egg maturation → maturing follicle produces oestrogen → rising oestrogen triggers an LH surge → LH surge causes ovulation.
The pill provides a constant, artificially elevated level of oestrogen throughout the cycle. This tricks the pituitary into "thinking" oestrogen is always high, so it suppresses FSH and the LH surge never occurs. Without the LH surge, ovulation does not take place. The pill essentially flatlines the normal hormone fluctuations that drive the cycle.
Why progesterone-only methods work: Progesterone inhibits both FSH and LH from the pituitary and causes significant thickening of cervical mucus. In high enough doses (implant, injection), it suppresses ovulation entirely. At lower doses (mini-pill), ovulation may still occur occasionally but cervical mucus becomes hostile to sperm penetration.
Quick Check: Explain, using the role of FSH, why taking a pill containing oestrogen and progesterone prevents pregnancy.
The combined oral contraceptive pill contains synthetic oestrogen and progesterone. Oestrogen inhibits FSH secretion from the pituitary gland. FSH is the hormone responsible for stimulating eggs to mature in the ovaries. Without FSH, no eggs mature, so ovulation cannot occur. With no egg present, fertilisation is impossible. Additionally, progesterone thickens cervical mucus, making it harder for sperm to reach the uterus even if ovulation were to occur. The pill therefore prevents pregnancy primarily by preventing egg maturation through FSH inhibition.
Quick Check: A student says "condoms are less reliable than the pill so there is no benefit to using them." Evaluate this statement.
The statement is partially inaccurate and ignores important benefits. While it is true that with typical use, the combined pill (91%) is more effective at preventing pregnancy than condoms (85%), this difference largely reflects user error (missing pill doses) rather than an inherent superiority. With perfect use, condoms are approximately 98% effective. Furthermore, the statement overlooks a major advantage of condoms: they are the only contraceptive method that protects against sexually transmitted infections (STIs). The pill provides no protection against STIs. For complete sexual health protection, condoms may be used alongside hormonal contraception. Therefore, the statement is misleading — condoms offer a benefit the pill cannot provide.
Quick Check: Compare hormonal and non-hormonal methods of contraception. In your answer, give one advantage and one disadvantage of each approach.
Hormonal contraception (e.g., pill, implant): Advantage — very high effectiveness (over 99% for implant with no user error); once fitted/taken correctly, does not require action at the time of intercourse. Disadvantage — does not protect against STIs; may cause hormonal side effects (mood changes, nausea); requires medical prescription. Non-hormonal contraception (e.g., condoms): Advantage — condoms protect against both pregnancy and STIs; available without prescription; no hormonal side effects. Disadvantage — more dependent on correct use at the time of intercourse; typical use effectiveness is lower than hormonal methods. Both approaches prevent pregnancy but address different risks.