How do you figure out when you conceived

July 14, 2018

Knowing the exact day of conception is a difficult thing. Sperm can live in a woman’s body for up to five days, making it impossible to calculate exactly when conception occurred. It is not a fine science.

In addition, women ovulate anywhere from 11 to 21 days after the first day of their last period. Ovulation varies from person to person. This is the reason why due dates are calculated from the 1st day of the last period and not from the date of conception.

Even though this can seem confusing, it has become a standard way of measuring pregnancy and calculating a due date. The due date is normally set at 40 weeks after the first day of the woman’s last period.

Fortunately, an ultrasound can help to determine gestational age. Ultrasounds are usually most accurate between the 8th and the 18th weeks. With an ultrasound, even women who don’t have periods at all can tell how far along they are.

Since only about 5% of all babies are actually born on the due date, this is only an estimation to begin with. Each baby and woman are unique individuals with their own timetables for birth. All we can do is give them a general idea what to expect!

Assure Women’s Center: If You Think You Might be Pregnant, We’re Your Best First Step!

Chances are you already know you’re pregnant. Getting pregnant might have been emotionally and physically hard, and taken a long or unexpectedly short time. Everyone reacts differently.

Missed period

The first sign of pregnancy is usually missing a period, about 2 weeks after you’ve conceived. This isn't always reliable and if your periods aren’t regular you might not notice you’ve missed one.

Some women have a bit of bleeding as the egg embeds. Many women also experience tender breasts. This may be around the time they would have expected a period and can be confusing.

Home pregnancy test

A home pregnancy test is a reliable way of checking to see if you’re pregnant. You can do a test on the first day your period's due.

The test measures a hormone called human chorionic gonadotrophin (hCG) in your urine. For the result to be positive, your body must be making enough for the test to pick it up, usually about 2 weeks after you conceive.

You can get a free pregnancy test, support and advice at a sexual health clinic.

Find a sexual health clinic in your area

Assisted conception

If you’ve had assisted conception (such as IVF), you need to wait about 2 weeks after the transfer of an embryo before doing a pregnancy test.

When you find out you’re pregnant, you’ll have an ultrasound scan. From then on, you’ll have the same care as other pregnant women.

Dating your pregnancy

The start of your pregnancy's dated from the first day of your last actual period, although you probably conceived about 2 weeks after that. That means by the time you miss a period you could technically be 4 weeks pregnant if you have a 28-day cycle. But every woman's different.

Pregnancy usually lasts between 38 and 42 weeks. Your due date will be estimated when you attend your first ultrasound scan appointment. Most babies are born in the 2 weeks before or after this date.

When you know you're pregnant

As soon as you know you’re pregnant:

• phone your GP practice and ask how to make an appointment with a midwife
• stop drinking alcohol as there's no safe amount to drink
• make sure you eat a healthy diet and start taking folic acid
• be active every day and drink plenty of water to prevent constipation
• stop smoking and don’t take drugs
• you must stop dieting as you must not go on a weight-loss diet in pregnancy
• tell your GP, midwife and obstetrician if you’ve had mental health issues before

Seeing your midwife early

Seeing a midwife as early in your pregnancy as possible gives you and your baby the best start. You'll be able to discuss how your lifestyle might impact on your baby and the choices you can make during pregnancy.

How you might be feeling

You might be feeling:

• overjoyed and excited
• have mixed emotions or not feel the way you expected

Maybe your pregnancy is a surprise and it’s taking a while to get used to the idea. Your partner can feel the same.

Talk about your feelings

Whatever your situation, it’s important to talk about how you’re feeling and make sure you’ve got support.

Your midwife's there for you, dads and partners too.

If you’ve got any worries or questions, the people involved in your care are happy to listen and help give you the support you need.

Your privacy

Sometimes young people worry about sharing their pregnancy with a professional.

Young people aged 13 and over have the same rights to medical confidentiality (privacy) as an adult and the same rights and responsibilities as all parents.

It’s important you're able to:

• access the care and support you need and are entitled to
• speak to an adult you trust so you can get the support you need during your pregnancy and once your baby's born

Your midwife can help you find out more about the support available from the NHS and other services.

Confidentiality

Your midwife or doctor won't tell anyone else about your pregnancy without your agreement if they believe:

• you fully understand the information and decisions involved
• there's no risk to your health or wellbeing

More about your right to confidentiality when using the NHS

Family Nurse Partnership

Most first-time young mums are eligible for support through the Family Nurse Partnership (FNP).

Specially trained FNP nurses:

• work with and support first-time young mothers during pregnancy and their child’s first 2 years
• can put you in touch with local young parent groups, where you can meet other young parents

The Scottish Government has more information about Family Nurse Partnership

Translations and alternative formats of this information are available from Public Health Scotland.