4 weeks pregnant: what's happening to you and your baby

You're in your first trimester, around 1 month pregnant. How your baby is growing at 4 weeks, what you might be feeling, and what to sort this week.

Your baby at 4 weeks

Your baby is a tiny embryo, tucked inside the amniotic sac and fed by a small yolk sac.

Its outer layer of cells will go on to become the placenta.

Your body at 4 weeks

You almost certainly don't look pregnant yet. With a first baby, many people don't show until at least 12 weeks.

You might notice nothing at all, or a missed period, sore breasts, tiredness, nausea, needing to wee more, or light spotting and cramping.

If you're staring at a faint line at 6am wondering if it counts: a line is a line. Make the call to your GP or midwife when you're ready.

Your to-do list at 4 weeks

Start taking 400 micrograms of folic acid a day, and keep going until at least 12 weeks.
Contact a midwife or GP to arrange your booking appointment, which usually happens between 8 and 12 weeks.

When to call your midwife

Contact your midwife, GP or NHS 111 if you have bleeding, tummy pain or severe sickness where you can't keep fluids down. Call 999 if you have heavy bleeding, severe pain, pain in the tip of your shoulder or feel faint, as these can be signs of an ectopic pregnancy.

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How big is my baby at 4 weeks pregnant?

At 4 weeks, your baby is about 2mm, the size of a poppy seed.

How many months is 4 weeks pregnant?

4 weeks pregnant is around 1 month, in the first trimester.

What should I do at 4 weeks pregnant?

Start taking 400 micrograms of folic acid a day, and keep going until at least 12 weeks.

Keep reading

This guide is general information based on NHS week-by-week guidance, not medical advice. Every pregnancy is different, and baby sizes are averages. If you're worried about anything, contact your midwife, GP or maternity unit. See the NHS week-by-week guide.

If you’re trying to conceive (TTC), you probably know that there are certain foods and nutrients that become especially important once you’re pregnant. But nutrition plays a vital role even when trying to conceive, much like laying a strong foundation before constructing a house.

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In other words, nutrition is a key player in the TTC journey, but getting the right nutrients in the right quantities can be tricky. That’s where supplements come in. Just as you’d take a multivitamin to fill in nutritional gaps for optimal health, fertility supplements can give you that extra nutrient boost.

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Choosing supplements for your fertility journey

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