Effects of the Pill


How the Pill works

The Pill contains synthetic hormones. There are two general types of Pill

  • progestogen only (mini-pill)
  • combined progestogen-oestrogen (combined pill)

One effect is to suppress the triggering mechanism in the brain which causes the release of follicle stimulating hormone and luteinising hormone and thus prevent ovulation. The combined Pill suppresses ovulation in about 98% of cycles. The mini-Pill suppresses ovulation in about 40% of cycles.

The Pill also affects the natural functioning of the endometrium and the cervix. The effect on the endometrium is to disrupt the normal growth pattern so that it cannot sustain an embryo.

Progestogen stimulates the production of G mucus and thus aims to prevent sperm penetration and sperm survival.

Quotes from Professor Erik Odeblad

"The study of the effects of contraceptive pills on the cervix is a difficult task. A considerable amount of work is required for each patient and the time required spans many years, up to 10 years or more. Many women also want to change to other pills or to other methods of contraception, or perhaps now want to become pregnant. It also happens that some pills are withdrawn from the market. To these difficulties are added the normal age changes in the cervix and the dynamic processes which are of constant occurrence. After 3 and up to 15 months of contraceptive pill use, there is a greater loss of the S crypt cells than can be replaced." ("Some Notes on the Cervical Crypts", Professor Erik Odeblad, Bulletin of the Ovulation Method Research and Reference Centre of Australia, Vol 24 No 2 June 1997, p31)

"Regression when taking the Pill is different for estrogen-dependent crypts (L and S) and progesteron-dependent crypts (G) which may in part overdevelop." (See "Cervical Mucus and their functions", Erik Odeblad, Journal of the Irish Colleges of Physicians and Surgeons, Vol 26 No 1 January, 1997).

"These circumstances may be simply stated by the expression: a pregancy rejuvenates the cervix by 2-3 years, but for each year the Pill is taken, the cervix ages by an extra year." ("The Discovery of Different Types of Cervical Mucus and the Billings Method", Professor Erik Odeblad, Bulletin of the Natural Family Council of Victoria, ISSN 0321-7567, Vol 21 No 3 September 1994, pp3-35).


Thus the Pill changes the natural symptoms of fertility on which most modern natural family planning is based. There is a variable recovery period after use of the pill for these natural symptoms. It is possible for the cervical crypts to suffer severe atrophication from prolonged use of the pill (see Ageing of the Cervix).

Other Effects of the Pill

There are many side effects of the Pill. A comprehensive coverage of these is given in the following reference.

A Consumers Guide to The Pill and Other Drugs, John Wilks, B.Pharm, MPS, ALL Inc. Stafford Virginia, 1997, ISBN 1- 890712-25-6


Billings Method

Billings Method Natural Family Planning INDEX email address