Contraception

Course Overview

  • Course Code: DMST 244

  • Course Name: Obstetrics & Gynecology I

  • Module: 3.1 Physiology of the Female Reproductive Cycle: Contraception

Topics Covered

  • SAIT

  • Oral Contraceptives

  • Intrauterine Contraceptive Devices (IUCD)

Hormonal Birth Control Mechanisms

  • Hypothalamus:

    • Acts as the control center for the menstrual cycle.

    • Produces GnRH (Gonadotropin-Releasing Hormone).

    • Function of GnRH: Stimulates the anterior pituitary gland to produce FSH (Follicle-Stimulating Hormone) and LH (Luteinizing Hormone).

Negative Feedback Mechanism

  • If estrogen and progesterone levels are consistently maintained:

    • This exerts a “NEGATIVE FEEDBACK” on the hypothalamus, inhibiting the release of GnRH.

    • If GnRH is suppressed:

    • This subsequently suppresses the anterior pituitary gland's release of FSH and LH.

    • Resulting effects:

      • Inhibition of new follicle development and ovulation.

      • Progesterone modifies secretory activity of the vagina and cervix, making mucus thick and impenetrable to sperm.

Birth Control Pills (BCPs)

  • Combination Pills:

    • Contains a combination of progestin and estrogen.

    • Mechanisms of action:

    • Prevents ovulation.

    • Thickens cervical mucus to block sperm passage.

    • Thins the uterine lining (endometrium) to prevent implantation.

Endometrial Effects

  • Thin Endometrium:

    • The thinning of the endometrium is crucial for preventing successful implantation of a fertilized egg.

Intrauterine Contraceptive Device (IUCD)

  • IUCD Characteristics:

    • Can be made of copper or plastic.

    • Inserted by a physician.

    • Prevents implantation of fertilized eggs.

  • Types of IUCDs:

    • Hormonal IUCDs (Intrauterine Contraceptive System - IUCS):

    • Secretes hormones.

    • Examples:

      • Mirena (most common)

      • Other brands: Liletta, Kyleena, Skyla.

    • Copper IUDs:

    • Non-hormonal.

Detailed Description of Mirena

  • Mirena IUCD:

    • Hormonal device containing progestin.

    • Physical characteristics:

    • Small, soft “T” shaped device.

    • Effectiveness:

    • Approved for up to 8 years of use.

    • Greater than 99% effectiveness rate.

    • Mechanisms of action:

    • Thickens cervical mucus, preventing sperm from passing.

    • Thins the uterine lining to prevent implantation.

    • Physically inhibits fertilization due to positioning in the uterus.

    • May prevent ovulation.

Detailed Description of Copper T IUD

  • Copper T IUCD:

    • Non-hormonal device:

    • Small, soft T-shaped plastic device coated with copper wire.

    • Effectiveness:

    • Approved for up to 10 years of use.

    • Effectiveness rate ranging from 99.2% to 99.4%.

    • Mechanisms of action:

    • Increases inflammatory response, interfering with sperm motility and viability, thus preventing fertilization.

    • Irritates the endometrium to decrease implantation.

    • Does not prevent ovulation.

Additional Information

  • Source Reference:

    • Raatz Stephenson, S. Diagnostic Medical Sonography Obstetrics and Gynecology 3rd Edition.

    • Publisher: Lippincott Williams & Wilkins, 2012.