Fertile window period: when are you most fertile?

When planning a pregnancy, fertile window is a term you may hear a lot about. If you are actively trying to conceive it is important to understand what the fertile window is and when is it in your specific case.

You should also follow a healthy lifestyle and start taking pre-natal vitamins from 1 month before the ideal day of conception.

pregnant woman: fertile window intercourse results in pregnancy

What does fertile window mean? (Ovulation window)

The fertile window is a 6-day interval in which it is most likely to get pregnant. It starts 5 days before you ovulate, and it ends on ovulation day. While you may still be fertile before or after the fertile window, it is highly unlikely you will get pregnant when sexual intercourse occurs outside this 6-day interval.

When are you most fertile?

According to studies, the highest chances of getting pregnant are on ovulation day and on the two days before ovulation (3-days total) with lower, but not minimal or close to zero, chances of getting pregnant also in the 3 preceding days.

How to calculate ovulation day?

There are several methods to calculate and predict ovulation. Some are more reliable than others as the menstrual cycle not only varies in duration and in when ovulation occurs in different women, but also in the same individual from cycle to cycle. The “standard” menstrual cycle is 28-days long. Days 1-5 are menstruation days or when bleeding occurs and day 14 is ovulation day. In the real-world, menstrual cycles are generally 21 to 35 days long and both the length and the ovulation day may vary from cycle to cycle. While 28-days seems to be the average, the menstrual cycle can be as short as 19 days and as long as 60. To calculate your fertile window you can use one of the methods below or you can combine them for a higher accuracy.

Calendar Method for ovulation

This method may provide an indication on the fertility window, but it’s not really precise due to the high possible variability. You should subtract 10-16 days from the last day of your menstrual cycle, which is the day before the bleeding starts, and ovulation should generally occur in that window.

Calculating ovulation with the cervical mucus method

Cervical mucus detected at the vaginal introitus (the opening of the vagina) may provide indication on when your most fertile days are. Mucus production increases in the 5-6 days preceding ovulation because of the increased estrogen levels: at the beginning mucus is creamy and sticky, then mucus becomes clear, stretchy and slippery and the optimal timing for sexual intercourse should be at peak mucus production. The fertile window, following this method, lasts from the first day cervical mucus is detected up to 3-4 days after the peak production.

Basal body temperature method

The basal body temperature (BBT) is the human body temperature at rest. Right after ovulation, the body temperature rises slightly due to the surge in progesterone. The rise is about 0.2-0.3 °C (0.3-0.5 °F) so you need an accurate thermometer to use this method; the temperature should be taken every morning before getting out of bed and should be recorded on paper or by using a smartphone app. After a few months you may be able to see a pattern and predict when the surge in temperature will occur; you are most fertile in the 2-3 days preceding the increase in basal body temperature. This is not a very effective method as it will only tell you when/if ovulation has likely to be occurred, but you won’t really know when you are most fertile. When BBT increases for 3 consecutive days, you should have entered the post ovulatory phase. Keep in mind that body temperature is affected by many factors, including stress, poor sleep, drinking alcohol and minor infections like the common cold.

Urinary Hormones methods to predict ovulation

There are many home test kits sold in stores that measure the levels of luteinizing hormone (LH). Once the LH is detected in urine, ovulation usually takes place within 12-24 hours; you should check your urine from at least 2 days before the expected ovulation day and continue until it is detected.

Ultrasound detection of ovulation

This method is very precise, but it is also time-consuming, inconvenient and expensive. By having a series of transvaginal ultrasounds, it is possible to monitor the ovarian follicle maturation and to identify when it ruptures and releases the egg in the fallopian tube.

Frequently Asked Questions on getting pregnant

Fertility, pregnancy and how to get pregnant are topics that generate a lot of confusion and a lot of questions. I answered some of the most frequently asked questions here below.

Can you get pregnant at any time of the month?

No, you can only get pregnant during your fertile window. The fertile window may be variable and occur earlier or later on some months.

Can you get pregnant after ovulation?

12-24 hours after ovulation the egg leaves the fallopian tube and can’t be fertilized by sperm anymore. The chances of getting pregnant 24h or more after ovulation are extremely low.

Can you get pregnant 3, 4, 5 days before ovulation?

Yes, you can. The fertile window is a 6-days interval that lasts from 5 days before ovulation to the day you ovulate. Days 3, 4 and 5 before ovulations are among the fertile days that are likely to result in a pregnancy.

Can you get pregnant with an IUD?

Yes, only abstaining completely from sexual activities gives a 100% guarantee of not getting pregnant. With IUDs, there is a 1 in 1000 chance of getting pregnant.

Can you get pregnant while on birth control?

Yes, there is no 100% effective birth control method. If you take the birth control pill, it is 99.7% effective if taken every day, but the effectiveness gets lower and lower if you forget to take it some days. To increase the effectiveness of birth control you should combine two or more methods, such as the pill used in conjunction with the condom.

Can you get pregnant with your tubes tied?

If you want to conceive after tubal ligation this is still possible: you can either have a “tubal reversal” surgery or you can do IVF. If you are wondering whether tube ligation will prevent 100% of pregnancies or not, according to studies there is still a 1 in 1000 chance to get pregnant after 1 year and between 2 and 10 in 1000 after 5 years.

Can you get pregnant from precum (pre-ejaculation)?

Yes, even precum may contain sperm capable of making you pregnant. For this reason, having your partner to come outside the vagina is not a safe birth control practice.

Can you get pregnant after menopause?

After menopause you no longer produce eggs and for this reason it is not possible to get pregnant naturally. It is still possible to get pregnant with assisted reproductive technologies: if for some reasons you froze some of your eggs you can still do IVF cycles; another option is doing IVF with donor eggs in countries where this practice is considered legal.

How long after stopping birth control can you get pregnant?

According to some studies, previous contraception is likely to delay your pregnancy. The time will depend on the type of contraceptive and how long for it has been used. With condoms or diaphragm, you may get pregnant as soon as you stop using them; with oral contraception (birth control pills) your pregnancy may be delayed 3-12 months. If you are using a contraceptive injection such as Depo-Provera your pregnancy may be delayed by up to 1-2 years. Since it is safe to conceive right after quitting any contraception method, don’t let these figures discourage you: while they may prove to be true in some people, results vary widely; think of those who get pregnant while taking the birth control pill!

What positions are best to get pregnant?

There is no evidence of any sexual position increasing the chances of getting pregnant; those that allow for deeper penetration such as the missionary or doggy style may deliver the sperm closer to the cervix, but according to science sperm can reach the fallopian tubes in as little as half an hour, so there is no need to help it by delivering it deeper.

Should I lay flat after sex to increase the chances of getting pregnant?

There is no evidence that lying flat on your back, putting a pillow under your hips or raising your legs in the air helps with conceiving. The important thing is for the ejaculation to happen completely inside the vagina, then the sperm is able to travel from there. If it makes you feel more confident to stay in bed 5-10 minutes before standing up or other of such practices, you can do it: although there is no evidence of increased success there is also no harm in trying.

How can I increase the chances of getting pregnant?

Besides trying to conceive at the right time in the menstrual cycle, both you and your partner should follow healthy routines such as eating a healthy balanced diet, eliminating or at least minimizing alcohol intake, quit smoking, have a healthy weight, engage in physical activities and limit caffeine intake to a maximum of 200 mg per day. Having sex once a day or once every other day seems to be best as both long period of abstinence and having sex too frequently may decrease sperm quality and chances of conceiving.

Does lube decrease the chances of getting pregnant?

Some in-vitro studies show that some types of lubricants such as Astroglide®, KY® Jelly, KY® TouchTM, saliva and olive oil may impair sperm motility hence decreasing the chances of getting pregnant, but an in-vivo study on human subjects did not confirm these findings. Nevertheless, the American Society for Reproductive Medicine advises mineral oil as the best option when a lubricant is needed.

How can I get pregnant fast?

The fastest way to get pregnant is for both partners to have and maintain a healthy weight, follow a healthy diet and lifestyle, and have unprotected sexual intercourse regularly during the fertile window.

When to see a doctor if you fail to get pregnant?

If you are a female over 35, you should get a specialist evaluation after 6 months of regular unprotected sexual intercourse without achieving a successful pregnancy.

For younger and healthy couples, it is advisable to get a consultation with a specialist after 12 months of failure to achieve a pregnancy. If you have any underlying condition, you should ask your GP for advice tailored to your specific case.

It is important to note that there is no 100% chance of conceiving even when timing, age and health status are all optimal. In the general population, every month (every menstrual cycle) there is a 15-25% chance of conceiving; by trying every month, the cumulative pregnancy rate gets higher and higher and for this reason it is advised to try for several months before consulting a specialist unless there are indications to do otherwise.



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