1-4 Weeks pregnant: Early Signs of Pregnancy

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^2.

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.

Early pregnancy symptoms⁵ 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)

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.

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
  
• Liver, and excessive consumption of foods high in vitamin A

Weight gain during pregnancy depends on your pre-pregnancy weight, and varies a great deal from mother to mother. Most women gain between 10kg and 12.5kg (22–28lb) while pregnant, some of which is the weight of the growing baby¹⁴. Learn everything you need to know about weight gain in pregnancy.