Your baby moves through different stages, starting as a blastocyst, then maturing into an embryo, and then a fetus. Around the five week mark, your baby’s heart will begin to beat, at 27 weeks they’ll have regular sleep and wake cycles, and at 39 weeks your baby is physically developed.
Your baby is an embryo consisting of two layers of cells from which all her organs and body parts will develop. 4 weeks pregnant. 5 weeks pregnant. 6 weeks pregnant. 7 weeks pregnant. Twins – 3 weeks pregnant. Twins – 4 weeks pregnant.
In fact, the weight of baby’s brain grows by a third during the last 4 to 5 weeks before full term. 3 Your baby is also gaining weight steadily, putting on roughly 8 ounces (half a pound) each week. 2 With every ounce, more fat develops beneath baby’s skin and their skin becomes less wrinkled. 4