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Oral Contraception (OC) – The quick and dirty of the facts

Posted Feb 02 2012 4:40pm

Contraception is a very controversial topic in some medical and social circles. So my purpose is not to go in to the religious, moral, and ethical issues of contraception, but to have an informative discussion on the various types of contraception and family planning that is available to men and women alike, with some information about natural contraceptive methods. Ultimately it is up to you, your partner, and your physician to determine the best type of contraception that works best and fits into your lifestyle. I am not here to preach that abstinence or natural methods are the correct way to go, each type has its pros and cons attached.

The most common type of contraception includes oral birth control pills, condoms, withdrawal, abstinence, progestin implants, and IUDs. Here, I will be discussing the various oral contraceptives (OCs) that are available. The mechanisms of birth control is pretty straight forward: OCs alter ovarian hormones by providing a negative feedback to the hypothalamus, which decreases the amount of gonadotropin-releasing hormone (GNRH), which consequently decreases the pituitary release of FSH and LH (gonadotropins) that normally stimulates ovulation. As a result, ovulation does not occur, the endometrium does not grow to its normal size during a monthly cycle without birth control, and cervical mucous becomes increasingly thick and hostile to sperm motility and survival.

The theoretical failure rate of most modern contraception is 0.1%, due to problems of compliance, and an actual failure rate of 2-3%. This method of birth control is equivalent to that of surgical sterilization. Previously, WHO suggested that women over 40 do not take OCs, but now it has been revised that healthy, non-smoking, women can take OC medication until menopause.

So what is in an OC? Historically, there has only been just estrogen put into the contraceptive pills when it was introduced in 1960. However, now there are pills that contain combinations of estrogen and progestin, or just progestin alone, to be taken orally. However, progestin alone may result in abnormal or irregular bleeding, and may be less effective than estrogen and progestin combined. OCs are typically not advised to be administered during breastfeeding and lactation.

There are 3 General Types of OCs that are prescribed:
> Progestin Only
“Minipills”, not widely used in the US
Used with breast feeding women and women who have estrogen contraindications
Mechanism: Suppression of ovulation by dampening LH and FSH, increase in cervical mucus viscosity, reduction in endometrial glands, and reduced cilia motility in fallopian tubes to slow ovum transport
Efficacy: Within 24 hours, rapid distribution and elimination returns to baseline; requires consistent administration; failure rates up to 7% in the first year of use
Advantages: Thromboembolism is minimal, decreased dysmenorrheal, blood loss, and PMS symptoms; Fertility is re-established immediately after cessation
Disadvantages: Continued need for compliance; Backup methods of contraception may be necessary because pill is late if taken >3 hours after established time; Nausea, breast tenderness, H/A, amenorrhea common

> Combination
Examples: Yaz, Beyaz (same progestin and estrogen contents of Yaz, but with a folic acid metabolite, levomefolate Ca+2)
Monophasic: constant dose of both estrogen and progestin in each pill
Phasic: can alter either or both hormonal components (use should be initiated either on the first day of menses or the first Sunday after menses has begun)
If forgotten: Should take 1 tablet as soon as she remembers, then she takes 1 tablet twice daily until coverage has been achieved. If a woman has missed more than 2 pills, backup contraception is advised
Mechanism of Action: Prevention of ovulation by inhibiting FSH and LH, altering cervical mucous, tubal transport, and endometrial lining
Efficacy: Failure rates range from 0.1% with perfect use to 5% with typical use
Advantages: Tx for menstrual irregularity and mittelschmerz; Anemic patients can increase their iron stores. Manipulation of cycle and prevention of benign breast dz, PID, and functional cysts
Disadvantages: Nausea, breast tenderness, breathrough bleeding, amenorrhea, headaches; No protection from STDs; Daily administration (See other contraindications above)
CI: CV dz, Coronary artery dz, DVT hx, Pulmonary embolism, CHF, untreated HT, Diabetes, estrogen dependent neoplasias, BrCA, Abnormal vaginal bleeding, Pregnancy, Lv dz, >35 years old, smoking, kidney or adrenal gland insufficiency (because drospirenone is anti-mineralocorticoid properties)

> 91 day combination
Contains: Progestin (levonorgestrel) and estrogen (ethinyl estradiol) + 7 days of placebo
Problem = lots of bleeding in between cycles
Contains: 30 mcg ethinyl estradiol, 150 mcg levonorgestrel, and 7 days of 10 mcg ethinyl estradiol (instead of placebo)
No hormone-free weeks occur
Advantages: Diminishes unplanned bleeding and spotting fewer symptoms
Disadvantages: Increased risk of blood clots and other cardiovascular effects

What are the special instructions on how to take the OC? Typically the woman is to take an oral pill for 3 weeks, and then during the 4th week, there is no hormone administered, to allow for withdrawal bleeding. Recently there are newer designs of OCs that include taking an oral pill for 12 weeks, while the 13th week administers no hormones, so that there may be withdrawal bleeding only 4 times a year.

What is the benefit to taking an OC? Well most important benefit would be the greater than 50% reduction in the risk of endometrial and ovarian cancers. Other protective effects include decreased incidences of benign epithelial ovarian tumors, abnormal uterine bleeding, dysmenorrhea, PMS, iron deficiency anemia, benign breast disorders, functional ovarian cysts, ectopic pregnancy, salpingitis (fertility impairment), and pregnancy.

Okay, so what are the potential risks?
> Breakthrough bleeding
> Pregnancy
> Harmful estrogen increases
> Hypercoagulability leading to DVTs and Thromboembolisms or Stroke
> Hypertension
> Breast Cancer
> Cervical Cancer
> Depression, headache, sleep disturbances
> Hyperglycemia
> Increased cholesterol
> Thyroid imbalances
> Vitamin Deficiencies (B vitamins and Vitamin C); Vitamin Toxicities (Vitamin A)

Please speak with your primary care physician if you think that taking an OC is right for you.

References Merck Manual
Medscape. “Contraception.”

Richard Dickey. Managing contraceptive pill patients. 2004

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