From Baby Center:
Head to rump, your baby is about 5 1/2 inches long (about the length of a bell pepper) and he weighs almost 7 ounces. He's busy flexing his arms and legs — movements that you'll start noticing more and more in the weeks ahead.
His blood vessels are visible through his thin skin, and his ears are now in their final position, although they're still standing out from his head a bit. A protective covering of myelin is beginning to form around his nerves, a process that will continue for a year after he's born. If you're having a girl, her uterus and fallopian tubes are formed and in place. If you're having a boy, his genitals are noticeable now, but he may hide them from you during an ultrasound.
Hungry? An increase in appetite is pretty common about now. Make it count by choosing meals and snacks that are rich in nutrients instead of empty calories (chips, French fries, candy, and other sweets). Bigger, more comfortable clothes are a must now as your appetite and waistline grow.
Your cardiovascular system is undergoing dramatic changes, and during this trimester your blood pressure will probably be lower than usual. Don't spring up too fast from a lying or sitting position or you might feel a little dizzy.
From now on, when you do lie down, it's best to lie on your side — or at least partly tilted to one side. (When you lie flat on your back, your uterus can compress a major vein, leading to decreased blood return to your heart.) Try placing a pillow behind you or under your hip or upper leg for comfort.
If you haven't already had a second-trimester ultrasound, you'll probably have one soon. This painless procedure helps your practitioner check how your baby's growing, screen for certain birth defects, check the placenta and umbilical cord, determine whether the due date you're working with is accurate, and see how many babies you're carrying. During the exam, you might see your baby moving around or sucking his thumb. Bring your partner along, and be sure to ask for a printout for your baby's first photo album!
Note from Jen:
Well, my 18th week was spent in China with Kenny and the baby-to-be. I did amazingly well (if I do say so myself) and managed to keep up with Kenny and climb to the top of the Great Wall!
I have been more hungry lately... good thing I packed fruit snacks and goldfish crackers to take on the trip. Yes Baby Center, I know I should be eating healthier snacks, but goldfish are just sooo good. I also ended up eating McDonalds 3 times on the trip... their soft serve ice cream was calling to me :)
This week, I had a few weird nights in Beijing when every time I fell asleep on my back, my right hand would fall asleep and then be numb for a while even after I woke up. I am trying my best to sleep on my side, but I am a back sleeper to the core so it has been tough.
I still am not too much bigger, but that should change soon. Here are a few 18 week pictures we took in China. The first is in the hotel at Xian (my pants are sticking out kinda funny near my belly cause there was no way I could button them with thermals on underneath! Ha Ha!). The second picture is in Shanghai on top of the world's tallest building standing on the glass floor!