So apparently week fourteen is the official start of the second trimester. During the fourteenth week the babies start growing at different rates, so from here on out we’ll be talking generalities. This week, little Pistachio is about the size of a fist and is starting to straighten out some and beginning to look more like a regular baby. The neck is lengthening and s/he should start growing hair, both on top of the head and on the eyebrows. Lanugo is growing in too. Lanugo is a coating of hair that acts like a blanket to keep the baby warm. Babies usually shed it by the time they’re born.