How time of sex affects pregnancy chances

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  • You will have a good chance of getting pregnant when have sex during fertile days
  • Timed intercourse is crucial for achieving pregnancy
  • Knowledge of signs of ovulation help for better planning of having intercourse



If you want to become a mother, timing is everything. If you want to get pregnant you should be healthy and at the same time, you have to be involved in regular and timed intercourse with your partner. Having unprotected sex during the fertile window period of your menstrual cycle improves your chances of getting pregnant.

Egg Releasing Time or Ovulation Time: Egg releasing time is most important if you want to become pregnant. There are more chances of getting pregnant if you have sex either on the day of your ovulation or two days before ovulation. In a normal menstrual cycle, you will have a few days in each month where your ovaries release an egg. This egg then moves to fallopian tubes to get fertilized with sperm for attaining pregnancy. This releasing of ripened or matured eggs by ovaries is called ovulation. Ovulation is defined as a physiologic process the rupture and release of the follicle from the ovary into the fallopian tube where it has the potential to become fertilized with the help of sperm. Ovulation occurs around day 14 of a typical 28-day menstrual cycle.[1]

If you are trying to conceive for a long time or if you are planning to grow your family, then it is important for you to know about your menstrual cycle and the best days (fertile days) to get pregnant. One of the easy and best methods to improve your chances is to follow timed intercourse.

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Timed intercourse improves your pregnancy chances

Timed intercourse is a simple and completely natural treatment approach. It is careful planning of your sexual intercourse during your fertile window period when you have a greater chance to conceive. It may sound odd, but timed intercourse brings the success of achieving pregnancy when done properly. One can track their ovulation by various body changes like increased cervical mucus or basal body temperature. If needed you can also consult a fertility expert, who can do a blood test to see progesterone level, to confirm ovulation and may also perform an ultrasound of the pelvis.

Ovulation happens about 14 days before your menstrual cycle starts, but women's period cycles are not all the same length. Women whose menstrual cycle length is 28 days, she will ovulate around day 14 and their best chance to conceive a baby is between days 11 and 14. For a woman whose cycle length is 24 days, ovulation happens around day 10 and her most fertile days are between days 7 and 10, while some woman who has a 35-day menstrual cycle will be most fertile between days 18 and 21, which will give you the best chance of conceiving.

One study shows that timed intercourse improved pregnancy rates when compared to intercourse without using ovulation prediction in couples who are trying to get pregnant [2].

First, we shall discuss the importance of a fertile window, as it is important for you to know your fertile days. You may know like any other trying to conceive couple that you will get pregnant when you have sex during your fertile window, which includes your ovulation days and the five days leading towards it. Let us know to identify your fertile window to attain successful pregnancy.


Fertile Window and planning of intercourse

The day you ovulate and the five days before ovulation is known as the fertile window. Outside this period of fertile window days, your chances of getting pregnant are very low.

At ovulation, an egg is released by ovaries and this egg moves down your fallopian tubes and survives there for 12 to 24 hours. Pregnancy is possible if sperm fertilizes your egg at this phase and if not fertilized, the egg will be absorbed by your body and is shed with uterine lining as menstrual bleeding. The fertility window begins approximately 3–5 days before the ovulation phase and continues to a point approximately 1–2 days after ovulation. Identifying this window is the most important step rather than simply identifying or detecting ovulation. [3].

According to some clinical guidelines in 30% of women, the fertile window is between days 10 and 17, and most of them reach the fertile window earlier while others get it later [4]. Even if your menstrual cycle is regular, your fertile window is highly unpredictable.

You will have a better opportunity to conceive within 24 hours of ovulation and one day prior to that. As the sperm can live in your reproductive system for 5 days and can fertilize your newly released egg which lives only for 12 to 24 hours after it is released, it is also possible for you to conceive if you have sex during five days before your ovulation time.

After 10 days of your last menstrual cycle, try having sex from the 11th day, and then continue for every other day. Follow this timed sexual intercourse for the next 10 days. This helps to store plenty of sperm even before your egg is released and also continues to add sperm while you ovulate, increasing the possibility of fertilization. Your chances of getting pregnant will be doubled when live sperms are available in your fallopian tubes while you are ovulating.

By keeping track of your menstrual cycle and knowing your fertile window you can plan sex at the right time and improve your chance of pregnancy. The following tips can help you to know your most fertile days.


How to track your fertile days

You can do the following things to track your cycle and your most fertile days to conceive.

  1. Tracking of your menstrual cycle: Maintain a menstrual diary to track the length of your menstrual cycle for a few months that helps to predict fertile window and ovulation. Then you can calculate the average length of your menstrual cycle.

The first day of your menses is said to be day one and ovulation occurs in about 14 days before your next period. For example, if the interval between periods is 28 days, then ovulation is expected to happen on day 14 and your fertile window falls between days 9 to 14. If the period gap is 30 days, you can expect ovulation on day 16th of your cycle and your fertile window days are from 11 to16 days respectively.

Even though your menstrual cycle is irregular, it is good to track your menstrual cycle. With the regular monitoring, you may notice some clues that give you a pattern of your period. It also helps fertility specialists to understand your cycle if needed.

2. Use an ovulation predictor kit ( OPK): There are a varied number of OPKs available at drug stores. If you are planning for pregnancy, you can use them to predict your ovulation and fertile window. OPKs work by monitoring luteinizing hormone (LH) levels in your urine, which is increased roughly 36 hours before ovulation. In case you have irregularity of your menstrual cycle, OPKs can still help you in identifying your ovulation time. Home urinary LH monitors are becoming more famous and widely available. It's a less expensive method to know the days of ovulation in real-time.

3. Notice symptoms of ovulation: Clinically, women who wish to plan a pregnancy or baby need to have intercourse on their fertile days. In order to identify the fertile period, it is important to track physiological parameters such as basal body temperature and not just length of menstrual cycle.[5]

You may experience secondary ovulation signs like a dull or sharp lower tummy pain, either on one side or on both sides. Tenderness of breasts increased sense of smell, taste, or vision, light spotting, and bloating are also seen commonly while ovulation. These symptoms are not a reliable way to predict ovulation but can still help you in predicting the days of ovulation. Common ovulation signs that most women experience are as follows [6]-

    • Cervical position: You can check your cervix position by placing a clean index and middle fingers inside your vagina. If the cervix is high and soft to touch like that of your lips and when you can’t feel it with your fingers, then you can expect your ovulation time to be approaching. At other times, the cervix is low and firm to touch like that of your nose tip.
    • Changes in cervical mucus: This is a natural and inexpensive method to track ovulation. If you notice slippery, clear, thick, and increased cervical mucus resembling the egg-whites, then it is a good time to have sex as you are ovulating.
    • Variations in basal body temperature: The body temperature at rest rises about 0.2 Celsius during your ovulation. Measuring your basal body temperature immediately after waking up from your bed can help to monitor ovulation. It helps to know your ovulation after it has occurred, so to confirm that you are ovulating and to have a track of your cycle pattern, tracking basal body temperature is important. Nowadays a basal body thermometer is available in the market to measure the basal body temperature (BBT). It is a good way to track ovulation in the low expense.

4. Check for changes in sex drive: While you ovulate, your ovaries release hormones that will increase your sex drive making it more convenient for getting pregnant.


Fertility chart to know your most fertile days

The fertile days and day of ovulation vary depending on the length of your menstrual cycle. Each woman is different with a different length of the menstruation cycle, so to calculate your menstrual cycle, count from the first day of your period to the day before your next period. This chart shows the most fertile days for some menstrual cycles with different lengths. You can check your ovulation days and fertile days below based on your average menstrual cycle length,

Menstrual cycle length

Day of Ovulation

Most fertile Day for Pregnancy

35 Days

Around day 21

19, 20 and 21 Days

32 Days

Around day 18

16, 17 and 18 Days

28 Days

Around day 14

12, 13 and 14 Days

24 Days

Around day 10

8, 9 and 10 Days

21 Days

Around day 7

5, 6 and 7 Days

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List of ReferencesHide

1 .

Holesh JE, Bass AN, Lord M. “Physiology, Ovulation”. In: StatPearls. Treasure Island (FL): StatPearls Publishing; June 16, 2020, PMID: 28723025.

2 .

Manders Marlies, McLindon Luke, et al.“Timed Intercourse for couples trying to conceive”.NCBI.NIH.GOV.Cochrane Database Syst Rev. 2015 Mar 17;(3): CD011345.PMID:25775926.

3 .

Su HW, Yi YC, Wei TY, et al. “Detection of ovulation, a review of currently available methods”. Bioeng Transl Med. 2017;2(3):238-246. Published 2017 May 16, PMID: 29313033.

4 .

Wilcox A J, Dunson D, et al.“The timing of “fertile window” in the menstrual cycle: day specific estimates from a prospective study”.PUBMED.NCBI.NLM.NIH.GOV.BMJ. 2000 Nov 18;321(7271):1259-62.PMID:11082086.

5 .

Bull JR, Rowland SP, et al. “Real-world menstrual cycle characteristics of more than 600,000 menstrual cycles”. NPJ Digit Med. 2019;2:83. Published 2019 Aug 27, PMID: 31482137.

6 .“Ovulation symptoms”, 02 September 2020.

Last updated on: : 28 Sep 2020

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