Patient's question:
Just after menstruation, having unprotected sex, how to prevent pregnancy? First follow-up question: Do I need to take emergency contraception?Doctor's answer:
Okay, here is the English translation of the provided text, following your instructions:I. Safe Period Contraception – Preventing pregnancy by avoiding sexual intercourse during the fertile period of the menstrual cycle.
1. The key to this method is determining the time of ovulation and avoiding sexual intercourse 48 hours before and after ovulation. Ovulation prediction can be estimated based on previous menstrual cycles (e.g., around day 14 of a 28-30 day cycle). An elevated basal body temperature (usually by about 0.5°C) or a change in cervical mucus (from watery to thick and stringy) also indicates ovulation.
2. Due to insufficient self-discipline or inability to accurately predict ovulation and potential extra ovulation, the failure rate is very high, reaching 25%. The advantage of this method is avoiding contact with stimuli or medications.
II. Barrier Contraception – Preventing sperm from entering the female upper reproductive tract to achieve contraception.
1. Male Condoms: A condom is placed over the penis before insertion into the vagina and before ejaculation. One size is generally available for everyone. However, it may reduce penile sensitivity.
2. Female Condoms: A pouch with two flexible rings is inserted into the vagina, with the open end remaining outside the vagina. One size is generally available for everyone, but it can appear somewhat bulky.
3. Vaginal Diaphragm: A dome-shaped latex membrane, the size should be individualized, placed in the posterior fornix of the vagina and between the pubic symphysis, with the spermicidal jelly-facing side towards the cervix. It should be inserted 1-2 hours before intercourse. Adverse reactions include bladder irritation.
4. Cervical Cap: A cap-shaped diaphragm, the appropriate size should be selected and placed on the cervix 2 days before intercourse. It may fall off during use and may not fit securely.
5. Spermicides: Formulations include foam, vaginal suppositories, and gel; they are placed inside the vagina. The spermicide nonoxynol-9 can destroy the lipid membrane on the surface of the sperm head and can also cause irritation to the genital tract mucosa.
Pros: No systemic adverse effects, relatively low cost, helps prevent certain sexually transmitted diseases.
Cons: Natural sexual pleasure during intercourse is reduced, relatively high failure rate (mainly due to forgetting to use it and improper use), up to 20%.
III. Intrauterine Device (IUD) – Interferes with endometrial maturation affecting implantation; alters tubal cilia activity affecting (egg) transport; interferes with the transport process of sperm from the cervix to the fallopian tubes; induces a leukocyte-dominated inflammatory response by the body towards the foreign object, causing local endometrial inflammation.
1. Progestin-releasing IUD: Must be replaced annually, can reduce menstrual cramps and bleeding.
2. Copper-releasing IUD: Needs to be replaced every 7 years, but may worsen menstrual cramps and increase menstrual flow.
Pros: High success rate, failure rate decreases after 35 years of age.
V. Contraceptive Methods with Uncertain Effectiveness
1. Coitus Interruptus: Withdrawing the penis before ejaculation. This method requires high self-discipline, and sperm may also enter the cervical mucus before ejaculation.
2. Post-coital Vaginal Irrigation: Rinsing the vagina to flush out semen. However, sperm can enter the cervical mucus within 90 seconds of ejaculation. Vaginal irrigation lowers the vaginal pH, making infection more likely.
3. Extended Breastfeeding: Continuously suppressing ovulation. While it can suppress ovulation, the delay in ovulation is uncertain and may only last for 3-6 months.