Your Pregnancy: Week 13

Your Baby
As the second trimester begins, your baby is growing quickly. She weighs about three-quarters of an ounce and measures between 2 1/2 to 3 inches from the top of her head to her bottom. She's in her fetal period, when the organs and tissues that took shape in the first trimester start to develop. Her intestines, originally part of the umbilical cord, have found a new home in her abdominal cavity. Her tongue and vocal chords are also getting ready for their debut at birth, and her eyes are moving closer together. Her ears are in place, and her head is roughly half the size of her whole body. (By birth, her head will be one-fourth the size of her body.)

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Your Body
If you have a checkup this week, your doctor or midwife may be able to feel the top of your uterus in the lower half of your abdomen. As it grows, your uterus will fill your pelvis, expanding up and out, and soon you'll definitely look the part of a pregnant woman.

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Do's and Don'ts
Do sign up now for childbirth classes, even though you won't be attending them for weeks (they usually begin in the seventh month). They're so popular that sessions fill up quickly. It's best to plan ahead to get the time slot that works best for you. Ask your doctor or midwife for a recommendation, or call your hospital or birthing center.

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Health
Studies show that moderate caffeine intake is fine for expectant moms, but too much can dehydrate you and leach your body's calcium, which your baby needs to grow strong teeth and bones. But coffee isn't the only caffeine-laden beverage out there. The ingredient is also found in soda, tea, and cocoa, so watch how much you indulge in these drinks, too, or pick decaffeinated alternatives.

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Mom to Mom

Advice from moms in the know: "Tell everyone that your delivery date is two weeks later than predicted. That way, friends and colleagues won't start checking up on you every day as 'the date' approaches." -- Stacey Pinnock, Salt Lake City

Shopping

Feeling hot, hot, hot? Choose natural fibers -- like cotton or linen -- over synthetics, which trap body heat and make you uncomfortable. If you're not sure of the weather, dress in layers, so you can easily add or remove them.

Exercise
Your fitness regimen is getting a makeover now that you're expecting. Avoid anything that requires the Valsalva maneuver, which happens when you exhale with great force (during weight lifting, for example); it can raise your blood pressure to dangerous levels.

Relationships
Experts say you should tell your boss before anyone else at work that you're pregnant, but it's hard to keep good news from friends. The alternative? Divulge your secret to coworkers whom you trust and who have been in the same situation. They can share their experience with you and give pointers on how to approach your supervisor or negotiate maternity leave.

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Siblings
When you're out and about at the park or the grocery store, start pointing out babies to your child. Remind him that the big event is around the corner by saying, "We're going to have one of those soon." Encourage him to talk about what he expects life will be like once he becomes a big brother.

Twins
Like other expectant moms, your body relies on your iron stores to support the placenta, only even more so since you're nourishing more than one baby. Incorporate lots of iron-rich foods like lentils, chickpeas, and leafy green vegetables in your diet, and ask your doctor about taking a supplement.