Pregnancy Week 2: Ovulation, Conception and Your Fertile Window

10 min read

Quick answer: Week 2 is when ovulation happens — an egg is released, and conception can take place if sperm are there to meet it. With a 28-day cycle this is usually around day 14, though it varies. The egg survives 12 to 24 hours and sperm up to 5 days, so your fertile window is roughly 5 to 6 days. Keep taking 400mcg of folic acid daily.

What parents need to know

Welcome to week 2 of pregnancy. As with week 1, it's worth remembering that in the NHS dating system, you're still not technically pregnant yet — but this week, everything changes. Week 2 is when ovulation occurs and, if conditions are right, fertilisation can take place. It's arguably the most biologically significant week of the entire conception journey.

Whether you're actively trying to conceive or simply curious about what happens in early pregnancy, understanding week 2 gives you a much clearer picture of how pregnancy begins.

Typical ovulation day	Around day 14 of a 28-day cycle
Egg survival	Approximately 12 to 24 hours
Sperm survival	Up to 5 days in the reproductive tract
Fertile window	Around 5 to 6 days
Folic acid	400mcg daily

What is happening in your body during week 2?

As week 2 begins, your menstrual period has ended and your uterine lining has started to thicken in preparation for a potential fertilised egg. The key event of this week is ovulation, the release of a mature egg from one of your ovaries.

The lead-up to ovulation

During the first half of your cycle (known as the follicular phase), follicle-stimulating hormone (FSH) causes several follicles in your ovaries to grow. Usually, one follicle becomes dominant and matures fully. As oestrogen levels rise, they trigger a surge in luteinising hormone (LH), and it's this LH surge that triggers ovulation.

For someone with a typical 28-day cycle, ovulation usually happens around day 14. However, cycles vary significantly, and ovulation can occur earlier or later. Women with shorter cycles may ovulate as early as day 10; those with longer cycles may ovulate on day 16, 18, or even later.

Ovulation

When the dominant follicle ruptures, it releases a mature egg (called an oocyte) into the fallopian tube. The egg can survive for approximately 12 to 24 hours. If it isn't fertilised within this window, it will dissolve and be reabsorbed by the body.

Sperm, by contrast, can survive in the female reproductive tract for up to 5 days. This means your fertile window — the time during which intercourse can result in pregnancy — is typically around 5 to 6 days: the 5 days leading up to ovulation and the day of ovulation itself.

Signs that you're ovulating

Not everyone notices ovulation, but many people experience one or more of the following signs:

Changes in cervical mucus: Around ovulation, vaginal discharge becomes clearer, wetter, and more stretchy — often described as resembling raw egg white. This texture helps sperm travel to the egg.
A rise in basal body temperature (BBT): After ovulation, progesterone causes a slight increase in your resting body temperature. Tracking BBT daily (before getting out of bed) can help you identify ovulation patterns over several cycles.
Mild pelvic pain: Some people feel a brief twinge or ache on one side of the lower abdomen around ovulation, known as Mittelschmerz (German for "middle pain").
Breast tenderness: Hormonal changes around ovulation can cause mild breast sensitivity.
Increased sex drive: Some people notice a natural rise in libido around ovulation, the body's way of encouraging reproduction.

Using ovulation predictor kits (OPKs)

Ovulation predictor kits, available from most UK pharmacies, detect the LH surge in your urine that occurs 24–36 hours before ovulation. They're a reliable and straightforward way to identify your most fertile days.

To use an OPK:

Start testing a few days before your expected ovulation (for a 28-day cycle, start around day 10–11)
Test at the same time each day — typically mid-morning is recommended
A positive result (two lines of equal darkness, or a smiley face on digital kits) indicates your LH surge has begun
Aim to have unprotected sex on the day of the positive result and the following one or two days

What happens if the egg is fertilised?

If a sperm successfully penetrates the egg in the fallopian tube, fertilisation occurs. The resulting cell (called a zygote) immediately begins dividing as it travels down the fallopian tube toward the uterus. This takes around 3 to 5 days.

By the time it reaches the uterus, the zygote has developed into a blastocyst, a ball of around 100 cells. The blastocyst will then attempt to implant into the thickened uterine lining. Successful implantation marks the true beginning of pregnancy, and this usually occurs during weeks 3 or 4 of the NHS dating system.

What to do this week

Whether you've already started your preconception preparations or you're just beginning, here's what to focus on during week 2:

Continue taking folic acid

If you haven't started already, begin taking 400mcg of folic acid daily right away. If conception occurs this week, folic acid will already be in your system to protect against neural tube defects during the critical early weeks of development. Do not take cod liver oil or supplements containing vitamin A (sometimes called retinol), and avoid liver and liver products, because too much vitamin A can harm your baby's development. Always check the label.

Track your fertile window

If you're trying to conceive, this is the most important week for timing. Using a combination of cervical mucus observation, BBT tracking, and ovulation predictor kits gives you the best chance of accurately identifying your fertile window.

Have regular, relaxed intercourse

While timing matters, the NHS advises that couples trying to conceive should aim to have regular sex (every 2 to 3 days) throughout the cycle rather than focusing exclusively on ovulation day. This reduces pressure and ensures sperm is available when the egg is released.

Maintain a healthy lifestyle

Avoid alcohol and smoking
Stay hydrated and eat a nutritious, balanced diet
Aim for 150 minutes of moderate exercise per week
Manage stress: chronic stress can affect hormone levels and ovulation
Avoid excessive heat (hot tubs, saunas) as this can temporarily affect sperm quality

When will you know if you've conceived?

If fertilisation and implantation are successful, your body will begin producing human chorionic gonadotropin (hCG), the hormone detected by pregnancy tests. However, hCG levels won't be high enough to detect until around week 4 (two weeks after ovulation, or around the time of your missed period).

The NHS recommends waiting until the first day of your missed period before taking a pregnancy test. Some early-response tests can detect pregnancy a few days before your period is due, but results are less reliable at this stage.

When to get help

Some symptoms in pregnancy can be a sign of something serious and need checking quickly. This is who to contact, and how soon.

Call 999 if:

you're bleeding from your vagina and the bleeding is heavy (soaking a period pad soon after putting it on), or you also have severe pain in your tummy, pain in your shoulder, or feel sick, faint, dizzy or lose consciousness
you have a sharp, sudden and intense pain in your tummy together with feeling very dizzy or fainting, feeling sick or looking very pale, as this could mean an ectopic pregnancy has ruptured (you can also go straight to A&E)
you have severe difficulty breathing (you're gasping, choking or not able to get words out) or your chest feels tight or heavy
you have pain and swelling in one leg and you also feel short of breath or have chest pain. A blood clot in the leg can travel to your lungs, which can be life-threatening
you have possible signs of sepsis, such as breathing very fast, being confused or having slurred speech, blue, pale or blotchy skin, a rash that does not fade when you press it, or a very high or very low temperature. Being pregnant makes sepsis more likely
you do not feel you can keep yourself safe (a mental health emergency is as serious as a physical one)

Always call 999 if you think it's a life-threatening emergency, no matter what stage of pregnancy you are.

Contact your GP or early pregnancy unit right away if:

you have light bleeding or spotting, even if you have no pain or only mild tummy pain
you have vaginal discharge that's unusual for you, or fluid leaking from your vagina
you have tummy pain low down on one side, or pain in the tip of your shoulder (where your shoulder ends and your arm begins). Symptoms of an ectopic pregnancy usually start between 4 and 12 weeks, so get advice right away, even if you have not had a positive pregnancy test yet
you have stomach pain that is severe or does not go away after you've rested for 30 to 60 minutes, or stomach pain with regular cramping or tightenings, lower back pain, or pain when you pee
your breathlessness comes on suddenly, you're out of breath when you're lying down, or you're breathless and also have chest pain or feel dizzy
you have pain or swelling in one leg, usually in the calf or thigh. This could be a blood clot (deep vein thrombosis, or DVT), which is more likely when you're pregnant
you have a high temperature (38C or above), or you feel hotter than usual or shivery. A high temperature can be a sign of an infection, so it's important to get it checked

If you cannot reach them, or you're not sure what to do, call NHS 111.

Speak to your GP or midwife if:

you're worried about your mental health, or stress, anxiety or low mood are affecting your day-to-day life. If you need urgent help for your mental health, call 111 and select the mental health option, or ask for an urgent GP appointment

Key takeaways

Week 2 is when ovulation occurs, the most fertile time in your cycle
The egg survives for 12–24 hours; sperm can survive for up to 5 days, making the fertile window around 5–6 days
Signs of ovulation include changes in cervical mucus, a rise in BBT, and mild pelvic pain
OPKs can help you identify the LH surge 24–36 hours before ovulation
If fertilised, the egg travels to the uterus and implants during weeks 3–4
Keep taking folic acid and maintain a healthy lifestyle

Frequently asked questions

When is the best time to have sex to conceive?

Aim for the day you get a positive ovulation test and the following one or two days. The NHS also advises having regular sex every 2 to 3 days throughout the cycle rather than focusing only on ovulation day.

When can I take a pregnancy test after ovulation?

hCG levels are not usually high enough to detect until around week 4, about two weeks after ovulation. The NHS recommends waiting until the first day of your missed period; earlier tests are less reliable.

How do ovulation predictor kits work?

They detect the LH surge in your urine, which happens 24 to 36 hours before ovulation. Start testing a few days before you expect to ovulate, test at the same time daily, and look for two equally dark lines or a smiley face.

Sources & further reading

General information, not individual medical advice. Speak to your GP, midwife or health visitor about your baby’s needs.