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What phase is best to get pregnant?

Getting pregnant can be an exciting yet stressful time for many couples. Knowing when you are most fertile can help maximize your chances of conception. The menstrual cycle is divided into different phases, each with varying levels of fertility. Tracking your menstrual cycle and identifying when ovulation occurs is key to understanding the fertile window. This article will examine the different phases of the menstrual cycle and determine which is the optimal time to conceive.

The Menstrual Cycle

The menstrual cycle is the process of hormonal changes that occur in the ovaries and uterus to prepare for pregnancy each month. It can be divided into three main phases:

Follicular Phase

The follicular phase spans from the first day of your period until ovulation. During this time, estrogen levels begin to rise which causes the lining of the uterus to thicken and mature. Several ovarian follicles also start to develop, each containing an immature egg. Typically one dominant follicle will emerge and continue to mature.


Ovulation occurs when the mature egg is released from the dominant follicle. This usually happens about 10-16 days before the start of the next period. The egg is viable for 12-24 hours after ovulation. Ovulation can be identified by tracking basal body temperature, cervical mucus changes, ovulation predictor kits, or an ovulation tracking app.

Luteal Phase

After ovulation, the leftover follicle transforms into the corpus luteum which starts secreting progesterone. Progesterone helps thicken and prepare the uterine lining for implantation. The luteal phase lasts about 14 days on average, ending when progesterone and estrogen drop off which triggers menstruation.

The Fertile Window

The fertile window spans approximately 6 days – the 5 days leading up to ovulation and the day of ovulation itself. Having sex during this time gives you the highest chances of getting pregnant. Let’s examine why this window has the optimal conditions:

Sperm Survival

Sperm can survive inside the female reproductive tract for up to 5 days. Having sex in the days leading up to ovulation allows the sperm to be ready and waiting when the egg is released.


The egg is viable for only 12-24 hours after being released. Having sex on the day of ovulation or the day before ovulation gives the sperm the biggest opportunity to fertilize the egg.

Cervical Mucus

Cervical mucus during the fertile window becomes thin, slippery, and alkaline. This allows sperm to easily swim through the mucus and reach the egg. Right before ovulation, mucus reaches peak fertility.

LH Surge

About 24-36 hours before ovulation, the body releases a surge of luteinizing hormone (LH) which triggers the process of egg release. Having sex on the days of LH surge increases conception chances.

When is the Fertile Window?

Now that we understand why the fertile window offers the best odds for conception, let’s look at when it typically occurs:

Menstrual Cycle Phase Average Day Range
Follicular Phase Day 1-13
Ovulation Day 11-16
Fertile Window Day 10-15
Luteal Phase Day 15-28

As shown in the table, the fertile window typically occurs between cycle days 10-15 for women with a standard 28 day cycle. However, cycle length can vary from person to person. The best way to identify your personal fertile days is to track ovulation each month. Methods include:

Ovulation Prediction Kits

These test your urine for the LH surge that precedes ovulation. Begin testing 1-2 days before your expected ovulation.

BBT Charting

Basal body temperature spikes by 0.5-1°F after ovulation. Record your temperature each morning to detect the shift.

Cervical Mucus Monitoring

Check mucus color, texture, and volume to identify peak fertility days.

Ovulation Tracking Apps

Use period dates and symptoms to pinpoint average ovulation and fertile times.

How to Maximize Your Fertile Window

To take full advantage of your fertile window each month:

  • Have sex every 1-2 days during the window, not just on the day of ovulation
  • Use sperm-friendly lubricants like Pre-Seed
  • Stay lying down for 15 minutes after sex
  • Achieve orgasm to help sperm retention
  • Avoid activities that raise core temperature like hot tubs
  • Maintain a healthy diet and lifestyle

Following these tips can help optimize conception odds during the fertile phase.

Other Menstrual Phases

While the fertile window offers the best chance of pregnancy, conception is still possible outside of these days:

Follicular Phase

There is a very low chance of getting pregnant during menstruation and right after your period since no egg is present. However, having sex on the days leading up to the fertile window can still result in pregnancy by priming sperm.

Luteal Phase

Once ovulation has passed, your chances of conception significantly decrease. But pregnancy is still possible since sperm can survive for days inside the female reproductive tract. The egg is only viable for 12-24 hours after ovulation though.

Next Cycle Follicular Phase

It is extremely rare, but previous cycle sperm can survive inside the tubes until the next ovulation. So technically you could get pregnant from sex that occurred right before your last period if ovulation gets delayed.

Key Takeaways

  • The menstrual cycle can be divided into the follicular phase, ovulation, and luteal phase
  • The fertile window spans the 5 days before ovulation through the day of ovulation
  • This window offers the highest chances of conception due to optimal mucus, the LH surge, egg viability, and sperm survival
  • For a 28 day cycle with day 1 starting on the first day of your period, the fertile window is typically cycle days 10-15
  • Track your personal ovulation signs each month to identify your fertile window
  • Have frequent sex during the fertile days and follow tips to boost your odds
  • It is possible but unlikely to get pregnant outside of the fertile window


Timing intercourse during your fertile window is the most effective approach to maximize your chances of conceiving. While sperm can survive longer, the egg is only viable for about a day after ovulation. Having sex in the days leading up to and on the day of ovulation allows conception to take place during the critical fertile phase. Tracking ovulation each month with BBT, LH tests, mucus changes or apps helps pinpoint when to focus your efforts. Understanding your personal fertility signs and pattern empowers you to make the most of your menstrual cycle for pregnancy achievement.