Billing’s method of contraception refers to:
2.Cervical mucus method
4.Coitus interruptus method
Basis: These methods aim at avoiding sexual enter intercourse around ovulation.
The timing of ovulation can be judged either on calendar basis or on symptom basis
a. Rhythm Method/Calendar Method: It is based on ojjino knauss theory which states ovulation occurs on day 14 + 2 in a female with a regular 28 days cycle (i.e. avoid sex between 12 and 16 day)
But fertilisable span of sperm is 48 - 72 hours and Ova is 12 - 24 hours.
Therefore, unsafe period = 8 - 18 day (Failure rate = 25 - 35%)
But failure rate can be reduced if - sex is avoided from 7 to 21 days (Failure rate = 10%)
Thus, sex is safe only in the first and last 7 days of a menstrual cycle (Park 20/e, p 436)
In irregular cycle: Safe period is=
Shortest cycle - 18 (gives 1st day of the fertile period)
Longest cycle - 11 (gives last day of the fertile period).
Basal body temperature method
The woman takes her body temperature at the same time every morning before she gets out of bed or eats anything. The temperature will rise slightly (0.2-0.5°C) just after ovulation due to effect of progesterone. The couple are asked to avoid intercourse or use an alternative method of contraceptive from the first day of the monthly bleeding until 3 days after the temperature rise .Once the fertile period is over, they can have coitus.
Billing’s or Cervical Mucus Method: This method is based on the observation of changes in the characteristics of cervical mucus. At the time of ovulation - Cervical mucus is watery, clear (resembling raw eggs white), smooth, slippery and profuse. After ovulation, under the influence of progesterone, the mucus thickens and lessens in quantity.
This method makes use of at least two indicators to identify the fertile period. Usually the cervical mucus method and the BBT method are combined.
Withdrawal method or coitus interrupts means discharge of semen outside the female genitalia at the time of the intercourse.
Failure Rate-the typical failure rate of natural family planning method is 20 per 100 women in the first year of use but it can be reduced to 1-9% with correct usage and practise.