The important things are growing right now
At 4 weeks gestation, your fertilised egg - a.k.a. a zygote - is a ball of 32 cells. It's at this point that those cells then separate into three layers, which will soon develop into the placenta, and your baby's internal organs and their skin... So while your embryo might be tiny, some super important things are happening right now.
If you were to have an ultrasound now, you'd find a small circle at the centre of the sonogram, which is a little sac that acts as your embryo's cocoon, and it's called a 'gestational sac'.
Your baby is now the size of a...
Poppy seed. Those 32 cells are so tiny at this stage, that they're around 2mm in length, and will weigh approximately 0.04oz.
Pregnancy symptoms at 4 weeks
The fertilised egg that is currently burrowing into your uterus may cause you to shed a few spots of blood. Any pregnancy symptoms you won't have, but if so, they'll barely be noticeable to you. Nonetheless, if you're sensitive, you may experience fatigue, queasiness or bloating, and tenderness in your breasts.
If you take a blood test at the doctor's, it's possible to get a positive result now, however, if you test at home it's important to know that you may get a false negative at this stage.
Tips and advice for pregnancy at 4 weeks
Your body is working very hard to support your pregnancy, and so if you experience fatigue that is a normal response. As mentioned above, pregnancy symptoms may not be noticeable at this stage. At this stage, it's best to make sure that you're eating well... But you don't have to be afraid of everything you put in your mouth.