Four weeks into your pregnancy, your baby (now an embryo) consists of two layers of cells — the epiblast and the hypoblast. These eventually develop into all of your baby's organs and body parts. Two other structures that develop now are the amnion and the yolk sac. The amnion, filled with amniotic fluid, will surround and protect the growing embryo. The yolk sac will produce blood and help to nourish the embryo until the placenta takes over that role. Your Body The embryo continues to implant in your uterus, burying itself deep within the endometrium. Some women have slight cramping and spotting during this week while implantation happens. They might mistake this for a period, especially because this is around the time their monthly period was due. Once implanted, the embryo starts to make a hormone called human chorionic gonadotropin (hCG), which helps to maintain the lining of the uterus. It also sends a signal to the ovary to stop releasing an egg each month, which stops your monthly periods. hCG is the hormone that's measured in pregnancy tests. This week, a pregnancy test probably could detect your pregnancy. hCG also causes the symptoms of pregnancy, which might start now. Tiredness, tingling or aching breasts, or nausea also can happen with premenstrual syndrome (PMS). But by the end of this week, your period won't happen. Instead, your pregnancy is under way!
Your Baby's Development The tail at the bottom of your baby's spinal cord has shrunk and almost disappeared by this week. In contrast, your baby's head has been growing — it's quite large compared with the rest of the body and it curves onto the chest. By this week, your baby measures about 0.6 to 0.7 inches (16 to 18 millimeters) from crown to rump and weighs around 0.1 ounces (3 grams). The tip of the nose has developed and can be seen in profile, and flaps of skin over the eyes have begun to shape into eyelids, which will become more noticeable in the next few weeks. The digestive system continues to develop. The anus is forming, and the intestines are growing longer. Internal reproductive features, such as testes and ovaries, start to form this week. Your baby may make some first movements this week as muscles develop. If you had an ultrasound now, those movements might even be visible, but you won't be able to feel them for several more weeks. Your Body In preparation for your first prenatal visit, take the time to familiarize yourself with your family's health history and to review your medical records. Have you had any chronic illnesses, allergies, or surgeries? Are you taking any prescription medicines? Do you know of any genetic disorders that run in your family? Has your menstrual cycle been regular, and have you had any past pregnancies? What are your exercise habits? These are some of the things your health care provider will want to discuss with you, so it will help to have this information ready when you go.
Your Baby's Development Welcome to the second trimester of pregnancy! Your placenta has developed and is providing your baby with oxygen, nutrients, and waste disposal. The placenta also makes the hormones progesterone and estrogen, which help to maintain the pregnancy. By now, the baby's eyelids have fused together to protect the eyes as they develop. Once you take your newborn home, you might be wishing for those eyes to close once in a while so you can get some rest! Your baby might be able to put a thumb in his or her mouth this week, although the sucking muscles aren't completely developed yet. Your Body At your first prenatal appointment, your health care provider probably gave you a prescription for prenatal vitamins. Taking these supplements, in addition to eating a healthy diet, ensures your baby gets needed vitamins and minerals, such as folic acid, zinc, iron, and calcium, which aid growth and development. Talk to your pharmacist about the best way to take your vitamins (such as whether they should be taken with food.
Your Baby's Development Ears move to their final position and they stand out from the head. And start brushing up on your lullabies — in the coming weeks, your baby will probably be able to hear! The bones of the middle ear and the nerve endings from the brain are developing so that your baby will hear sounds such as your heartbeat and blood moving through the umbilical cord. He or she may even be startled by loud noises! Your baby's eyes are also developing — they're now facing forward rather than to the sides, and the retinas may be able to detect the beam of a flashlight if you hold it to your abdomen. Until now, your baby's bones had been developing but were still soft. This week, they begin to harden, or ossify. Some of the first bones to ossify are those in the clavicles and the legs. Your Body You're probably beginning to prepare for life with baby. This is a good week to begin your search for a pediatrician or other health care provider for your child. Schedule visits to meet with potential doctors to discuss issues such as appointment availability and when to call in an emergency. You'll also want to learn as much as you can about their practices and procedures. Some good questions to ask: How many health care providers are in the practice? Who covers nights and weekends? What is their policy on phone calls? Which hospitals are they affiliated with? What insurance do they accept? What specialists do they work with? How are emergencies handled? It's important that you feel comfortable with your child's doctor, so do your homework and make your decision carefully.
Your Baby's Development The senses your baby will use to learn about the world are developing daily. Taste buds have started to form on the tongue, and the brain and nerve endings are formed enough so that the fetus can feel touch. Your baby may experiment with this newfound sense by stroking his or her face or sucking on a thumb, as well as feeling other body parts and seeing how they move. Your baby's reproductive system continues to develop. In boys, the testes have begun to descend from the abdomen, and in girls, the uterus and ovaries are in place and the vagina is developed. Your Body If you haven't felt them already, you may soon notice your uterus practicing for delivery with irregular, painless contractions called Braxton Hicks contractions. You may feel a squeezing sensation in your abdomen. Don't worry, though: Your baby may be able to feel the contraction as it squeezes the uterus, but these aren't dangerous or harmful. But if the contractions become more intense, painful, or frequent, contact your health care provider immediately because painful, regular contractions may be a sign of preterm labor.
Your Baby's Development By this first week of the third trimester, your baby looks similar to what he or she will look like at birth, just thinner and smaller. The lungs, liver, and immune system still need to fully mature, but if born now, your baby would have a very good chance of surviving. As hearing continues to develop, your baby may start to recognize your voice as well as your partner's. Sounds may be muffled, though, because the ears are still covered with vernix, the thick waxy coating that protects the skin from becoming chapped by the amniotic fluid. Your Body Your body continues to protect and nourish your baby. But what happens when it's time to meet your little one? Consider signing up for childbirth classes through your local community center or hospital to learn about labor, options for pain relief, and what to expect after delivery. You'll also learn about common newborn problems, babyproofing, breastfeeding and formula feeding, and infant CPR. Learning all you can about birth and babies will help you feel more confident, especially if you're a first-time parent.
Your Baby's Development Your baby is peeing several cups of urine a day into the amniotic fluid. He or she is also swallowing amniotic fluid, which is replaced completely several times a day. Too much fluid in the amniotic sac (polyhydramnios) could mean that the baby isn't swallowing normally or that there's a gastrointestinal obstruction. Not enough fluid in the amniotic sac (oligohydramnios) could mean that the baby isn't peeing properly, which could indicate a problem with the kidneys or urinary tract. Your health care provider will measure your levels of amniotic fluid as part of your routine ultrasound. Your Body Have you decided whether to breastfeed or formula feed your baby? Experts recommend breast milk as the best form of infant nutrition, but the decision about how to feed your baby is a personal one. Talk to your health care provider or a lactation consultant if you need more information before making your choice. The milk glands in your breasts may have started to make colostrum by now. Colostrum is the pre-milk that provides your baby with calories and nutrients for the first few days before your milk comes in (if you plan to breastfeed). For some women, it is thin and watery. For others, it is thick and yellowish. If you notice your breasts leaking colostrum, you can buy disposable or washable breast pads to protect your clothing.
Your Baby's Development The tiny wrinkly fetus you saw on earlier ultrasounds is fast becoming a plump baby. Fat on the cheeks and powerful sucking muscles contribute to your baby's fuller face. Your baby now weighs a little under 6 pounds (2,721 grams). The bones that make up your baby's skull can move and overlap each other. This is called molding, and it helps the baby pass through the birth canal. Don't be surprised if your little one arrives with a pointy or misshapen head! After a few hours or days, your baby's head will be back to a rounded shape. Your Body You now might see your health care provider every week. Your doctor or midwife may do an internal exam to see if cervical effacement (thinning of the cervix) or dilation (opening of the cervix) has begun. The baby might drop into your pelvis in preparation for labor — this is called engagement or lightening. Your appetite may return because the baby isn't putting as much pressure on your stomach and intestines, and if you've had heartburn, that might ease.
You Baby's Development After months of anticipation and preparation, your baby is here! Or maybe not — most women don't deliver right on their estimated due dates. Many first-time moms find themselves waiting up to 2 weeks after their due date for their baby to arrive. A baby born at 40 weeks weighs, on average, about 7 pounds, 4 ounces (3,300 grams) and measures about 20 inches (51 cm). Don't expect your baby to look picture perfect right away, though — a newborn's head often is temporarily misshapen from the birth canal and may be covered with vernix and blood. Your baby's skin might have discolorations, dry patches, and rashes. This is all completely normal. Right after birth, your health care provider will suction mucus out of your baby's mouth and nose, and you'll hear that long-awaited first cry. Your baby may then be placed on your stomach, and the umbilical cord will be cut — often by the baby's dad, if he chooses to do the honors! A series of quick screening tests, such as the Apgar score, will assess your baby's vital signs and responsiveness. Then your little one be weighed and measured. If you had a high-risk pregnancy or a C-section, a neonatologist (a doctor who specializes in newborn intensive care) will be at your delivery to take care of your baby right away. Your baby will receive any special care needed to adjust to life outside the womb — and then will be placed in your waiting arms. Your Body This week is the moment you've been waiting for — you meet your baby! Before you do, though, you have to go through labor and delivery. You may have learned about the three stages of birth in your prenatal classes. The first stage of labor works to thin and stretch the cervix by contracting your uterus at regular intervals. The second stage is when you push your baby into the vaginal canal and out of your body. The third and final stage of labor is when you deliver the placenta. If you don't go into labor within a week of your due date, your health care provider may recommend you have a nonstress test. This monitors fetal heart rate and movement to be sure that the baby is getting enough oxygen and that the nervous system is responding. Your health care provider will tell you more about this test, if it's needed. If your labor isn't progressing, or if your health or your baby's health requires it, your health care provider may induce labor by artificially rupturing the membranes (breaking your water) or by giving you the hormone oxytocin or other medicines. A high-risk pregnancy or other potential complications may require a C-section delivery. Some women know ahead of time that they'll deliver via C-section so can schedule and prepare for their baby's "birth day" in advance. This might help to ease feelings of disappointment that moms who can't deliver vaginally sometimes have. If you had a C-section that wasn't planned, you may feel a little sad. Remember that having a C-section does not make your baby's birth any less special or your efforts any less amazing. After all, you went through major surgery to deliver your baby! Congratulations and best of luck with your baby!