1-4 weeks pregnant: Pregnancy Symptoms & Baby Development
Read time: 4 minutes
One to four weeks pregnant is how many months?
Month 1 (Trimester 1)
Baby development at 1-4 weeks
During the 90 hours after fertilisation, cells divide and subdivide into a tiny mass.
Placenta
Learn about the role of your placenta.
Vitamin C
Discover how vitamin C supports us for life.
Baby development at 1-4 weeks
How big is my baby? And what does my baby look like?
At this stage, there’s not much to see. Your newly-fertilised egg is called a zygote1. 90 hours after fertilisation, cells divide and subdivide into a tiny mass that will travel from your fallopian tubes to your uterus. After four weeks, your baby will be the size of a poppy seed and will be protected by an amniotic sac. This is filled with cushioning fluid, and attached to a tiny yolk sac that provides your baby with nourishment. The outer layer will develop into the placenta, providing your baby with oxygen and nutrients.
Around 6-10 days after ovulation you may notice some light spotting as the bundle of cells, now known as a blastocyst, attaches to the wall of your womb.
Early stage pregnancy
Body changes
It’s unlikely you’ll look pregnant: most first-time mums don’t start showing until at least week 12. It’s unlikely you’ll feel pregnant, too, but that will change when the ‘pregnancy hormone’ – human chorionic gonadotrophin2 – becomes active. That said, you’re starting to grow a brand new organ – the placenta.
By week 4 of pregnancy, your baby will get their nourishment from a tiny yolk sac, but this will be replaced by the placenta2. This brand new organ will supply your baby with oxygen and nutrients needed to grow and develop. It also passes antibodies to your baby, for resistance to infection throughout pregnancy3.
Another function of the placenta is hormone production3. These hormones help your baby grow and develop while supporting your own physical changes. Progesterone and relaxin, for example, both have a relaxant effect on your muscles, allowing your uterus to adapt and make room for your growing baby4.
Pregnancy symptoms at 1-4 weeks
Early pregnancy symptoms can be subtle, and are sometimes missed. That said, it’s possible you may experience some of the following:
- A missed period
- A need to wee more frequently
- A metallic taste in your mouth
- Changing tastes in food Morning sickness
- A milky white discharge from your vagina (perfectly normal)
Focus on Vitamin C
Vitamin C is a vital nutrient in the first 4 weeks of pregnancy. It plays an important role in keeping cells healthy and contributes to normal collagen function. Collagen gives support and structure to tissue and organs such as skin, blood vessels and cartilage6, and is one of the building blocks of your rapidly growing placenta.
Vitamin C supports the immune system by keeping cells healthy and helping wounds to heal.
Foods to avoid while pregnant
There’s nothing specific to avoid during individual weeks, but throughout your pregnancy, it’s wise to give the following a miss:
Raw and undercooked meat
Unpasteurised milk and dairy products