Your baby is about the size of an orange this month, and growing! See whats happening during weeks 13 to 16.\r<br>\r<br>During week 13, pick up a clementine—thats how big your baby is now! For more on your little ones fetal development (big stuff happens this month), check out .\r<br>\r<br>Welcome to week 16 of pregnancy. Your avocado-sized fetus is growing so rapidly, and moving so much, that you may feel those first fluttering movements now!\r<br>\r<br>Is your pregnancy test positive? Congratulations! Heres what to expect during weeks one through four.