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Week 2
Although you're not pregnant yet, you may be about to release an egg that could grow into a baby if it's fertilized by a sperm. At the beginning of this week (around day 15 of a 28-day cycle), you may ovulate. When this happens an egg erupts from its follicle and is swept from your ovary into a fallopian tube. During the next 24 hours, that egg will be fertilized if one of the nearly 250 million sperm in each ejaculation can penetrate the egg. -
Week 5
Deep in your uterus your embryo is growing at a furious pace. At this point, he's about the size of a sesame seed and looks more like a tiny tadpole than a human. He's now made up of three layers – the ectoderm, the mesoderm, and the endoderm – which will later form all of his organs and tissues. Many women report sore breasts, fatigue, and frequent urination starting in the early weeks. You may also have nausea, though it's more likely to show up in the coming weeks. -
Week 10
Though he's barely the size of a kumquat – a little over an inch or so long, crown to bottom – and weighs less than a quarter of an ounce, your baby has now completed the most critical portion of his development. This is the beginning of the so-called fetal period, a time when the tissues and organs in his body rapidly grow and mature. He's swallowing fluid and kicking up a storm. Vital organs – including his kidneys, intestines, brain, and liver are in place and starting to function. -
Week 15
Your growing baby now measures about 4 inches long, crown to rump, and weighs in at about 2 1/2 ounces (about the size of an apple). Her legs are growing longer than her arms now, and she can move all of her joints and limbs. Although her eyelids are still fused shut, she can sense light. If you shine a flashlight at your tummy, for instance, she's likely to move away from the beam. Though you're well into the pregnancy by now, you still might be surprised by some symptoms. -
Week 20
Your baby weighs about 10 1/2 ounces now. He's also around 6 1/2 inches long from head to bottom and about 10 inches from head to heel – about the length of a large banana. Your baby is swallowing more these days, which is good practice for his digestive system. He's also producing meconium, a black, sticky by-product of digestion. This gooey substance will accumulate in his bowels. Congratulations! You've hit the halfway mark in your pregnancy. -
Week 25
Your baby now measures about 13 1/2 inches. Her weight, 1 1/2 pounds, isn't much more than an average rutabaga, but she's beginning to gain some baby fat. As she does, her wrinkled skin will begin to smooth out and she'll start looking like a newborn. She's also growing more hair. Your hair may look fuller and more lustrous than ever. It's not that you're growing more hair, but thanks to hormonal changes, the hair that you'd normally shed is sticking around longer than usual. -
Week 30
Your baby is about 15.7 inches long now and weighs almost 3 pounds (about the size of a large cabbage). A pint and a half of amniotic fluid surrounds her, but that volume will shrink as she gets bigger and takes up more room in your uterus. Her eyesight continues to develop, even after she's born, she'll keep her eyes closed for a good part of the day. When she does open them, she'll respond to changes in light but will have 20/400 vision – which means she can only see a few objects up close. -
Week 35
Your baby doesn't have much room to maneuver now that he's over 18 inches long and tips the scales at 5 1/4 pounds (about the size of a honeydew melon). Because it's so snug in your womb, he isn't likely to be doing somersaults anymore, but the number of times he kicks should remain about the same. His kidneys are fully developed now, and his liver can process some waste products. Most of his basic physical development is now complete. He'll spend the next few weeks putting on weight. -
Week 40
After months of anticipation, your due date rolls around, and ... you're still pregnant. It's a frustrating, but common, situation. You may not be as late as you think, especially if you're relying solely on a due date calculated from the day of your last period. You still have a couple of weeks before you'll be considered "post-term." But to be sure your baby is still thriving, your doctor or midwife will schedule you for testing if your pregnancy continues.
