Contraception Lecture by Dr.Mohammed Sharique Ahmed Quadri Assistant professor ,Physiology Al Maarefa College

Contraception Is prevention of pregnancy before the implantation has taken place .

Methods of Contraception Blockage of sperm transport to ovum Natural Methods Rhythmic abstinence Coitus interruptus Barrier methods Use of spermicidal Sterilization tubal ligation vasectomy Prevention of ovulation Hormonal contraceptive (OCP) Blockage of implantation IUCD Emergency contraception/morning after pill

Natural Methods of Contraception Rhythmic abstinence Coitus interruptus periodic or rhythmic abstinence i.e. avoidance of sexual intercourse during woman’s fertile period Following methods are used Calendar method: The women predicts when ovulation to occur based on keeping careful records of previous cycles First fertile period is shortest cycle minus 18 & last fertile period is longest cycle minus 10

Natural Methods of Contraception Basal body temperature method: Body temperature rises slightly a day after the ovulation safe period is considered to begin after the basal body temperature remains elevated for 3 days Cervical mucus method : ovulation time is determined by noting the consistency of the cervical mucus Coitus interruptus: withdrawal before ejaculation

Barrier methods: prevents entry of sperm into vagina or uterus For males (condom) For females ( diaphragm or cervical cap ) Spermicidal: Suppositories Gel Foam tablets creams

Permanent Methods Female sterilization ( i.e tubal ligation or Tubectomy) Male sterilization (vasectomy):

Prevention of ovulation Hormonal contraceptive Oral contraceptives Combined pills Progesterone only pill Once a month pill Injectable

Hormonal contraceptive(continued) Oral contraceptives Contains synthetic estrogen and progesterone like steroids (ethinyl estradiol & norgesterel/norethesterone) Tablets are taken once daily for 21 days commencing at 5th day of menstrual cycle ,it is than stopped for 7 days during which time bleeding occurs Mechanism of action: They act by inhibiting the release of FSH & LH by anterior pituitary by negative feedback mechanism, preventing the development of graffian follicle ,ovulation & formation of corpus luteum is prevented Increases viscosity of cervical mucus ,preventing the sperm penetration Endometrial maturation is also altered preventing blastocyst implantation

Hormonal contraceptive(continued) Injectable long acting prgestational preparation which can be given once in a three months Sub dermal implants of progesterone have also been tried Dermal patch , vaginal rings

Blockage of implantation Intra Uterine Contraceptive Device(IUCD): Are devices which are introduced & left inside the vagina for longer period of time . They are of two types Unmedicated devices as Lippe’s loop Medicated devices as copper –T They are usually changed after three years

Intra Uterine Contraceptive Device(IUCD)(continued) Mechanism of action : They produce local nonspecific inflammatory reaction in the endometrium & prevent implantation of blastocyst . Copper increases cellular response & may alter the composition of cervical mucus It is also believed that IUD increases the motility of fallopian tube ,so ovum reaches the uterus either before it is fertilized, or if fertilized before endmetrium is ready for implantation. Recently hormone releasing IUCD’s have been devised .for e.g. progetasert releases progesterone which act locally on the endometrium & cervical mucus .

Intra Uterine Contraceptive Device(IUCD)(continued) Side effects : Bleeding Abdominal pain / backache Displacement Perforation

Blockage of implantation (continued) Post coital /morning after pill it is used as emergency contraceptive measure after unprotected sexual intercourse( most effective within 72 hours ) It acts by preventing ovulation or cause premature degeneration of corpus luteum, thus preventing the implantation. The WHO-recommended regimen for emergency contraception is: 1.5 mg of levonorgestrel as a single dose.

Future possibilities Immunocontraception : in the testing stage is the vaccine that can induce formation of antibodies against human chorionic gonadotrophin Male birth control pill: some scientist are seeking ways to manipulate the hormones to block the spermatogenesis One interesting avenue is being explored to use the Ca blocking drugs ,as Ca is responsible for sperm motility

Average failure rates of common contraceptive techniques Contraceptive method Average failure rate (100 women-year) Natural method 20-30 Chemical contraceptive 20 Barier method 10-15 OCP 2-2.5 IUCD 4

References Human physiology by Lauralee Sherwood, seventh edition Current Obstetrics & Gynecology diagnosis & treatment