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