Safe Period to Have Sex and Avoid Pregnancy: Understanding the Reproductive Cycle and Fetal Development

Is there a safe period when you can have sex with your male/female partner and still avoid pregnancy? There is no 100% fool proof method to avoid pregnancy without any contraceptive or a barrier, but you can increase the odds of avoiding pregnancy if you know a little bit about a woman’s reproductive system and menstrual cycle. Most of the fundamentals of the reproductive cycle are straightforward: a healthy normal woman menstruates once every 28 days on an average, and day one is always the day when the periods start.

Fundamentals of the Reproductive Cycle

To understand the safe period, one must recognize that an egg is released by the ovaries into the fallopian tube in the middle of the menstrual cycle. An egg lives inside the body of the woman for 24 hours waiting for a sperm to fertilise it. If the egg doesn’t fertilise during its 24 hours life span, it is absorbed back by the body. However, a man’s healthy sperm can live inside a woman’s body for 5 days and in rare cases up to 7 days.

Can a woman get pregnant if she has unprotected sex with a man during her period? Short answer – no. During periods, the inner lining of the uterus, which is called ‘endometrium’, is removed from the uterus and pushed out. This means all the contents of the uterus are also pushed out including any sperm that might enter; so, having sex while a woman is menstruating doesn’t induce pregnancy.

Calculating the Safe Period

Assuming a woman menstruates for 28 days, 14 day will be the middle of the cycle during which she theoretically ovulates. As the sperms stay alive for 5 days inside the woman’s body, unprotected sex must be avoided from 9th day. To be on the safer side, just leave another 2 days for ovulation, that will be the 16th day. Having unprotected sex from 17th day reduces the odds of pregnancy. The closer the woman goes to having her next period, the lower the chances of getting pregnant. Because a couple of days here and there may change, it is always best to have unprotected sex (to avoid pregnancy) after 18 days after pregnancy.

Tools to Track Ovulation

There are simple tools that you can use to know when you are ovulating to plan your fun accordingly:

• Measuring basal temperature: You need a basal thermometer to use immediately after you wake up. You should see a very slight increase a day before and on the day of ovulation.
• Checking the mucus in your cervix: During the days of ovulation, there will be an increase in the amount of mucus in the cervix region.
• Ovulation prediction kits: These kits measure the amount of luteinizing hormone in the urine, which increases 24 to 48 hours before ovulation.

Methods of Contraception

Beyond natural timing, there are different methods of contraception to avoid pregnancy including:

• Everyday birth control pills
• On-demand birth control pills
• Intra Uterine Device (IUD) – hormonal and non-hormonal (copper based)
• Contraceptive injections

From experience, a recommendation is to go for non-hormonal copper based IUD. This tiny device is made from pure copper and is placed inside the uterus; the copper metal kills the sperms and acts as a spermicide.

Critical Periods of Development and Birth Defects

Understanding pregnancy also involves knowing the critical periods of development. These are times during pregnancy when the fetal organs and body parts are forming. During these times, the fetus is especially sensitive to things that could cause harm. Most birth defects happen in the first trimester of pregnancy, which ends at 13 weeks and 6 days since a person’s LMP (last menstrual period).

Timing of Fetal Development

The following summary provides data on the sensitivity of development stages:

• First Trimester: Major structures of the body (including the heart, arms, legs, lips, and palate) form.
• Second and Third Trimesters: Some exposures can cause problems with how the body part works, known as functional defects.
• Functional Defects: Examples include intellectual disability and hearing loss, which usually develop after the first trimester.
• General Risk: Out of all babies born each year, about 3 out of 100 (3%) will have a birth defect.

Once a body part has finished forming, exposures are less likely to cause major structural defects. For example, if a medication is taken at 20 weeks, the risk of cleft lip is very low because the lip is already formed by week 9.