🤰 Pregnancy Due Date Calculator

Use our free Pregnancy Due Date Calculator to estimate when your baby will arrive. Enter the first day of your last menstrual period for your estimated due date, current week and trimester based on Naegele’s Rule.

NHS Maternity Care Pathway

The National Health Service provides comprehensive maternity care free of charge to all women in the United Kingdom, regardless of nationality or immigration status. When you discover you are pregnant, your first step is to contact your GP surgery, who will refer you to a midwife for your booking appointment, ideally before 10 weeks of pregnancy. At this appointment your midwife will take a detailed medical history, arrange blood tests, discuss screening options, and issue your handheld maternity notes.

NHS maternity care follows two main pathways. Midwife-led care is recommended for women with uncomplicated, low-risk pregnancies. Your midwife acts as your primary carer, and you may choose to give birth at a midwife-led birthing centre or at home. Consultant-led care is recommended for higher-risk pregnancies, including those involving pre-existing medical conditions, complications such as preeclampsia or gestational diabetes, or previous caesarean sections. Under consultant-led care, you will see an obstetrician at certain appointments alongside your midwife, and birth takes place in a hospital labour ward with full medical facilities.

NICE Guidelines for Prenatal Appointments

The National Institute for Health and Care Excellence (NICE) sets out a recommended schedule of antenatal appointments. For a straightforward first pregnancy, NICE recommends approximately 10 appointments. Women who have had a baby before typically need around 7 appointments. The standard schedule includes:

Booking appointment (8-12 weeks): Comprehensive health assessment, blood tests (blood group, rhesus status, full blood count, sickle cell and thalassaemia screening, hepatitis B, HIV, syphilis), and urine tests. Screening options for Down's syndrome, Edwards' syndrome, and Patau's syndrome are discussed.
Dating scan (8-14 weeks): The first ultrasound confirms the pregnancy, checks the number of babies, and provides an accurate estimated due date based on the crown-rump length measurement. This date may differ from your LMP-based calculation.
Combined screening test (11-14 weeks): Blood test measuring PAPP-A and hCG levels combined with nuchal translucency measurement from the dating scan to assess risk of chromosomal conditions.
16-week appointment: Review of test results, blood pressure and urine check, discussion of any concerns.
Anomaly scan (18-21 weeks): A detailed ultrasound examining the baby’s organs, bones, brain, and spinal cord. Checks for 11 specific physical conditions. The sonographer can usually tell you the sex of the baby if you wish to know.
25-week appointment (first pregnancy only): Measure the bump (symphysis-fundal height), check blood pressure and urine.
28-week appointment: Blood tests (full blood count, antibodies), anti-D injection if rhesus negative, blood pressure and urine check.
31-week appointment (first pregnancy only): Review blood test results, check blood pressure and bump measurement.
34-week appointment: Blood pressure, urine, second anti-D injection if rhesus negative, discuss birth plan and labour preparation.
36-week appointment: Check baby's position, discuss birth plan including pain relief options, breastfeeding, vitamin K, and newborn screening.
38-week appointment: Blood pressure, urine, discuss options if baby is overdue.
40-week appointment (first pregnancy): Discuss membrane sweep and induction options if you go past your due date.
41-week appointment: Offer membrane sweep and discuss induction of labour, typically offered between 41 and 42 weeks.

Ultrasound Scans During Pregnancy

The NHS routinely offers two ultrasound scans during pregnancy. The dating scan at 8-14 weeks establishes your due date and checks for multiple pregnancies. The anomaly scan at 18-21 weeks is a detailed examination of the baby’s development. Additional scans may be arranged if there are concerns about growth, placental position (particularly if placenta praevia is suspected at the anomaly scan), or if you have risk factors such as gestational diabetes or pre-existing conditions. Growth scans in the third trimester typically measure the baby’s head circumference, abdominal circumference, and femur length to estimate weight.

Fetal Development by Trimester

First Trimester (Weeks 1-12)

During the first twelve weeks, all major organs begin to form. The neural tube (which becomes the brain and spinal cord) develops in weeks 3-4. The heart begins beating at approximately 6 weeks. By 12 weeks, the fetus measures around 6 centimetres and weighs about 14 grams. Limbs, fingers, and toes are fully formed, and facial features are recognisable. This is the period when the fetus is most vulnerable to external factors, which is why folic acid supplementation and avoiding alcohol are so important.

Second Trimester (Weeks 13-26)

The baby grows rapidly, developing fine hair (lanugo), eyebrows, and eyelashes. Movements become strong enough for the mother to feel from around 18-22 weeks. The baby can hear sounds from outside the womb from about 18 weeks. By 24 weeks the baby is considered viable (capable of surviving outside the womb with intensive medical care), weighing approximately 600 grams.

Third Trimester (Weeks 27-40)

The final trimester focuses on growth and maturation. The lungs develop surfactant (essential for breathing after birth), the brain grows rapidly, and fat stores build up for temperature regulation. By 36 weeks, most babies have turned head-down in preparation for birth. A full-term baby at 40 weeks typically weighs between 3 and 4 kilograms.

Maternity Pay and Leave in the UK

Eligible employees in the UK are entitled to up to 52 weeks of maternity leave, comprising 26 weeks of ordinary maternity leave and 26 weeks of additional maternity leave. Of these, 39 weeks are paid through Statutory Maternity Pay (SMP): the first 6 weeks at 90% of your average weekly earnings, followed by 33 weeks at the standard rate (currently £184.03 per week in 2025/2026 or 90% of average weekly earnings, whichever is lower). The remaining 13 weeks are unpaid.

To qualify for SMP you must have worked for your employer continuously for at least 26 weeks by the 15th week before your due date, and earn at least £123 per week (the lower earnings limit). If you do not qualify for SMP, you may be eligible for Maternity Allowance from the government, paid at £184.03 per week (or 90% of average earnings) for up to 39 weeks.

Shared Parental Leave (SPL) allows eligible parents to share up to 50 weeks of leave and 37 weeks of pay between them. This provides flexibility for both parents to take time off with the baby. The mother must curtail her maternity leave to activate SPL. Partners are also entitled to 1-2 weeks of paternity leave at the statutory rate.

Birth Plan Options

The NHS encourages women to consider their birth preferences and discuss them with their midwife. Available options include:

Hospital labour ward: Full medical facilities with obstetricians, anaesthetists, and neonatal specialists available. Recommended for higher-risk pregnancies. Epidural anaesthesia is available.
Midwife-led birth centre: A more relaxed environment staffed by midwives, often with birthing pools and a home-like atmosphere. Suitable for low-risk pregnancies. If complications arise, transfer to a labour ward can be arranged.
Home birth: Supported by the NHS for low-risk pregnancies. A midwife (or two midwives during delivery) attends your home. NICE guidelines note that for second or subsequent low-risk pregnancies, giving birth at home is as safe as giving birth in a midwife-led unit or hospital. For first pregnancies, there is a slightly higher rate of transfer to hospital.

Your birth plan might include preferences for pain relief (gas and air, pethidine, epidural, water birth), birthing positions, who you want present, delayed cord clamping, skin-to-skin contact, and feeding intentions. Remember that birth plans are flexible guides rather than rigid schedules, as circumstances can change during labour.

Signs of Labour

As your due date approaches, be aware of these signs that labour may be starting:

Regular contractions: When contractions come at regular intervals, growing longer, stronger, and closer together. Contact your maternity unit when contractions are about 5 minutes apart and lasting 60 seconds.
Waters breaking: A gush or trickle of clear fluid. Note the colour and time, then contact your maternity unit. If the fluid is green or brown, go to hospital immediately as it may indicate meconium.
Show: A pink or blood-streaked jelly-like plug of mucus from the cervix. Labour may follow within hours or days.

Ring your maternity unit for advice if you are unsure whether you are in labour. They will ask about the frequency and intensity of contractions and guide you on when to come in. If your waters break before labour begins (premature rupture of membranes), most units recommend induction within 24 hours to reduce infection risk.

Nutrition and Supplements During Pregnancy

The NHS recommends the following key nutrients during pregnancy:

Folic acid: 400 micrograms daily from the time you start trying to conceive until 12 weeks of pregnancy. This reduces the risk of neural tube defects such as spina bifida. Available free through the NHS Healthy Start scheme for eligible women.
Vitamin D: 10 micrograms (400 IU) daily throughout pregnancy and breastfeeding, as recommended by NICE. Essential for bone health of both mother and baby.
Iron: Not routinely supplemented unless blood tests show low levels. Eating iron-rich foods such as lean red meat, beans, lentils, and fortified breakfast cereals helps maintain healthy levels.
Omega-3 (DHA): Found in oily fish such as salmon, mackerel, and sardines. The NHS recommends eating two portions of fish per week, one of which should be oily, but no more than two portions of oily fish per week during pregnancy.

Foods to avoid during pregnancy include raw or undercooked meat, liver and liver products (too much vitamin A), unpasteurised milk and cheese, raw shellfish, shark, swordfish, and marlin (high mercury content), and more than 200mg of caffeine per day (roughly two mugs of instant coffee). The NHS advises that there is no safe level of alcohol consumption during pregnancy.

Weight Gain During Pregnancy

NICE does not set specific weight gain targets during pregnancy, unlike some other countries. However, the general guidance is that most women gain between 10 and 12.5 kilograms (22 to 28 pounds) during pregnancy. Women who are overweight or obese before pregnancy are advised to gain less. Your midwife will monitor your general health throughout pregnancy but does not routinely weigh you after the booking appointment unless there are concerns. If you have questions about weight management during pregnancy, discuss them with your midwife or GP, who can refer you to a dietitian if needed.

Frequently Asked Questions

How accurate is the due date calculator?

The due date calculated using Naegele's Rule is an estimate. Only about 5% of babies arrive on their exact due date. Most births occur between 37 and 42 weeks. Your dating scan at 8-14 weeks provides the most accurate due date, particularly if it differs from the LMP-based date by more than 5-7 days.

When should I contact my GP about my pregnancy?

Contact your GP surgery as soon as you get a positive pregnancy test. They will arrange a referral to the midwifery team for your booking appointment, which should ideally take place before 10 weeks. Early booking ensures you can access all recommended screening tests within the correct timeframes.

What happens if I go past my due date?

Going past your due date is very common, especially with first pregnancies. The NHS will offer you a membrane sweep at 40 weeks (first pregnancy) or 41 weeks, and induction of labour is typically offered between 41 and 42 weeks. Your midwife will discuss the options and monitoring available if you prefer to wait for spontaneous labour.

Is the anomaly scan mandatory?

No NHS scans are mandatory; all are offered and you can decline. However, the anomaly scan at 18-21 weeks is strongly recommended as it checks for 11 specific physical conditions and can identify issues that may need treatment before or after birth. The scan is free of charge and takes approximately 30 minutes.

Can I have a home birth with the NHS?

Yes, the NHS supports home births for women with uncomplicated, low-risk pregnancies. NICE guidelines state that for women having their second or subsequent baby, home birth is as safe as hospital birth. One or two midwives will attend your home during labour. If complications arise, transfer to hospital will be arranged by ambulance.

What maternity pay am I entitled to?

If you qualify for Statutory Maternity Pay (SMP), you receive 6 weeks at 90% of your average weekly earnings, followed by 33 weeks at the standard rate of approximately 184 pounds per week. You need to have worked for your employer for at least 26 weeks by the 15th week before your due date. If you do not qualify, Maternity Allowance may be available at a similar rate.