Month 1: The Beginning
Weeks 1–4 of Pregnancy
The first month of pregnancy, from conception to implantation.
Welcome to the miraculous beginning of your pregnancy journey. Though you may not even know you are pregnant yet, incredible changes are already taking place. This first month includes conception, fertilisation, and the earliest stages of your baby's development.
What is happening this month
The first month of pregnancy is counted from the first day of your last menstrual period (LMP). This means that during the first two weeks, you are not actually pregnant yet. Conception typically occurs around week 2 or 3, when ovulation happens.
Week-by-week development
Your menstrual period begins. Every month, your body is preparing for potential pregnancy.
Ovulation occurs. An egg is released and moves along your tube ready for fertilisation.
Fertilisation happens. The sperm meets the egg, creating what is known as a zygote that begins dividing rapidly.
Your baby (called a blastocyst at this stage) implants in your uterine lining. You might experience some implantation bleeding.
Your baby's development
By the end of month 1, your baby is tiny, about the size of a poppy seed (0.1–0.2mm). Despite this microscopic size, crucial development is already underway:
- The blastocyst continues to divide into hundreds and thousands of cells
- The placenta begins to form
- The amniotic sac starts developing
- The foundation for all major organs is being laid
- Basic genetic characteristics are determined
Size comparison
Your baby is about the size of a poppy seed
0.1–0.2 mmChanges in your body
During the first month, you might not notice many changes, especially in the first few weeks. However, as implantation occurs and hormone levels begin to rise, you may experience:
Implantation Bleeding
Light spotting when the embryo attaches to the uterine wall
Fatigue
Feeling more tired than usual due to rising progesterone
Temperature Changes
Basal body temperature remains elevated after ovulation
Breast Tenderness
Breasts may feel fuller or more sensitive
Cramping
Mild cramping as the uterus begins to change
Missed Period
The most obvious sign, occurring at the end of week 4
Important care tips
Start folic acid
Begin taking folic acid (400 micrograms daily), ideally three months before conception or as soon as possible to prevent neural tube defects. In the UK, folic acid is available free on prescription for pregnant women. A good antenatal vitamin supplement ensures you are getting essential nutrients.
Healthy lifestyle
Maintain a balanced diet rich in fruits, vegetables, whole grains, and lean proteins. Stay hydrated and avoid alcohol, smoking, and excessive caffeine. One cup of light filter coffee a day is considered acceptable.
Medical review
Review any medications with your GP or pharmacist. Some medications may need to be adjusted, changed, or stopped for pregnancy safety.
Gentle exercise
Continue your usual exercise or introduce a gentle routine. Walking, swimming, and antenatal yoga are excellent choices that can be maintained throughout pregnancy.
When to contact your GP, maternity unit or call 999
If you experience any of the following, contact your GP or go directly to your nearest maternity assessment unit. In an emergency, call 999.
- Heavy bleeding (more than a normal period)
- Severe abdominal pain or cramping
- Dizziness or fainting
- Fever over 38°C
Looking ahead
As you enter month 2, you will likely discover you are pregnant through a positive home pregnancy test. This is an exciting time to contact your GP practice to register your pregnancy and book your first midwife appointment, which typically happens around 8 weeks. Remember, every pregnancy is unique, and it is normal to feel a mix of emotions as you process this life-changing news.
Frequently asked questions
In month 1, pregnancy begins with conception, fertilisation, and implantation. The baby is the size of a poppy seed but key development such as the placenta and amniotic sac has already started.
Early signs may include a missed period, implantation bleeding, breast tenderness, mild cramping, fatigue, and a rise in basal body temperature.
Take a home pregnancy test after you miss your period, typically at the end of week 4. For the most accurate results, test with your first morning urine when hCG levels are highest. If you test too early, you may get a false negative.
Yes. Most home pregnancy tests can detect hCG (the pregnancy hormone) around the time of a missed period, typically at the end of week 4.
Yes, it is completely normal. Many women do not experience noticeable symptoms until weeks 6–8 when hormone levels rise significantly. Every pregnancy is different.
Avoid raw or undercooked meats, fish high in mercury, unpasteurised dairy products, raw eggs, unwashed vegetables, and excessive caffeine. Avoid alcohol completely.
Avoid alcohol, smoking or vaping, recreational drugs, and excessive caffeine. Always review medications with your GP or pharmacist to confirm they are safe in pregnancy.
Take folic acid (400 micrograms daily), maintain a balanced diet, stay hydrated, keep active with gentle exercise, and arrange a GP appointment once pregnancy is confirmed.
