It's getting crowded in there! You're gaining about a pound a week and roughly half of that goes straight to your baby, who's taking up more and more space in your uterus. In fact, she'll gain a third to half of her birth weight over the next seven weeks as she fattens up to prepare for life outside the womb. Her fingernails and toenails have grown in, and she's sporting hair – or at least some fluffy peach fuzz – on her head.
By now, your baby weighs 3 3/4 pounds (about the size of a large jicama) and is about 16.7 inches long, taking up a lot of space in your uterus. You're gaining about a pound a week and roughly half of that goes right to your baby. She'll gain a third to half of her birth weight during the next 7 weeks as she fattens up for survival outside the womb. She now has toenails, fingernails, and real hair (or at least respectable peach fuzz). Her skin is becoming soft and smooth as she plumps up in preparation for birth.
To accommodate your and your baby's growing needs, your blood volume has increased 40 to 50 percent since you got pregnant. And with your uterus pushing up near your diaphragm and crowding your stomach, the consequences may be shortness of breath and heartburn. To help relieve your discomfort, try sleeping propped up with pillows and eating smaller meals more often.
You may have lower-back pain as your pregnancy advances. If you do, let your doctor or midwife know right away, especially if you haven't had back pain before, since it can be a sign of preterm labor.
Assuming it's not preterm labor that's ailing you, you can probably blame your growing uterus and hormonal changes for your aching back. Your expanding uterus shifts your center of gravity and stretches and weakens your abdominal muscles, changing your posture and putting a strain on your back. Hormonal changes in pregnancy loosen your joints and the ligaments that attach your pelvic bones to your spine. This can make you feel less stable and cause pain when you walk, stand, sit for long periods, roll over in bed, get out of a low chair or the tub, bend, or lift things.