Pregnancy is an amazing journey. While we often talk about it lasting for nine months, pregnancy is generally measured by weeks, lasting 40 weeks or 266 days from conception. Each month brings unique changes for your baby’s growth and development. Enjoy a tour through the entire length of pregnancy in ultrasound pictures and descriptions of how your baby is growing and changing at each stage of pregnancy.
These months are designed to be generic and may or may not specifically relate to your pregnancy. Please direct any questions you have about your baby's growth or your progress to your doctor or midwife. Pregnancy is a normal process and questions are a natural part of that process.
The beginning portion of what we consider the first month of pregnancy is actually your period until you ovulate. You are not actually pregnant during this time frame, but knowing the first day of your last normal period (LMP) we are able to more accurately calculate your due date.
Conception usually occurs within 24 hours of ovulation, about 14 days before the start of your next period. The egg and the sperm meet in the outer third of the Fallopian tube and travel over the course of the next seven to ten days, down the tube to the uterus. Once in the uterus, the fertilized egg will implant into the fluffy, nutrient rich lining of the uterus. Immediately chemical signals are sent to your body that pregnancy has occurred. Ovulation will halt. Your period will not come.
Your baby is called a blastocyst as it implants. The baby measures about 0.1-0.2 mm. At the end of the fourth week of pregnancy, the chorionic villi are formed. The yolk sac is helping to sustain the pregnancy until the placenta is fully formed. You might even begin to suspect you’re pregnant.
The second month of pregnancy is a critical month in fetal development. Your baby goes from being a blastocyst to an embryo. Early on in this month your baby’s heart will begin to beat. First it beats slowly, then very rapidly, later in pregnancy the heart rate will slow a bit more.
In the beginning of this month it’s hard to tell which way is up on your baby. As this month progresses it becomes very easy to tell which end is your baby’s head is and which end is your baby’s bottom. By the end of the month your baby’s upper and lower limb buds will also appear. And the primordia of the liver, pancreas, lungs, and stomach are evident. While your baby is a girl or a boy, it is not yet apparent without genetic screening.
Your baby is now measuring between 8-11 mm from crown to rump (CRL). By the end of this month heart activity is always present on ultrasound. Toe and finger rays are present, though not quite enough for you to count yet.
During the third month of your pregnancy, your baby’s bones begin to ossify or harden. Your baby is already moving spontaneously, but you usually can’t feel these movements for awhile yet. Your baby’s eyes are large and open. Eyelids will form later. External ears have formed.
External genitalia begin to differentiate, though it’s still very difficult to tell whether your baby is a girl or a boy without genetic screening. Your baby moves from being an embryo to the fetal period, now called a fetus. S/he also loses their tail!
Your baby’s head is the biggest part of their body. It is about 1/2 the size of the rest of the body. While the head is large, the brain’s structure is similar to what it will be at birth. S/he weighs about 14 grams and is approximately 3.54 inches in total length. By the end of this month you should be able to hear your baby’s heart beat with a Doppler.
The placenta has taken over production of the hormones needed to sustain your pregnancy. Your baby is also making some of its own insulin and bile. Your baby even urinates into the amniotic fluid in small amounts every 45 minutes or so.
Your baby’s heart pumps about 25 quarts of blood a day. This will increase to be about 300 quarts by the end of your pregnancy. All of the teeth have formed and you even have a scalp hair pattern!
Your baby is about 3 ounces (85 grams) and 6.3 inches (16 cms). The gender may be detectable by ultrasound. Though gender predictions at this point are much harder to rely on.
No new organ structures are really forming at this point in pregnancy. Though the pads of the fingers and toes are forming. Your baby is also developing his or her finger prints. Your baby is also forming permanent teeth buds behind the baby teeth that are already formed. A baby girl will also begin to develop primitive eggs in her ovaries. Gender is usually visible by ultrasound, though accuracy varies.
Your baby’s movements may be more apparent. Loud noises may even cause your baby to startle. It’s still pretty unusual for your to be able to feel your baby move at this point unless this is not your first pregnancy. You may be aware of sleep wake cycles in your little one.
Your baby is also covered in a fine hair called lanugo and may begin to develop a lotion like substances on their skin called vernix. The weight is now up to 10 ounces (283 grams) and the baby measures about 25 cms total length, about 9.8 inches.
Eye brows are forming now and the lanugo darkens in color. Your baby is moving and practicing breathing for when he or she will be born. The practice contractions that you may or may not notice don’t bother your baby one bit. Your baby may or may not be head down, because of the amniotic fluid your baby can move all around still.
Your baby is also depositing brown fat. The brown fat will help him or her regulate body temperature at birth. This brown fat will continue to be laid down until birth.
S/he weighs in at 1 lb 5 ounces (595 grams) and 30 cms or 11.8 inches total length. A few babies are born this early. They do have some chance of survival depending on many factors.
Baby’s movements at this point in pregnancy have gone from wild kicks and flurries to smaller movements as the room becomes crowded in the uterus. At about week 28 babies begin to start turning head down. This is automatic in most babies and they seem to like it that way.
Your baby can sense light and dark in the uterus. This may also effect the pattern you notice of sleep and wake cycles. The uterus is also not a silent environment. While the baby can hear your heart beat, your digestive system, etc. your baby can also hear your voice as well as others close by. Think of what you can hear in a pool.
Your baby's eye lashes are developing, as subcutaneous fat is deposited. If you have a baby boy, his testes will probably begin descending. Your baby is about 13.8 inches long (35 cms) and weighs about 2 pounds 4 ounces (1 kilogram)! A baby born at this time has a good chance of survival with the help of medical technology.
Your baby is really getting ready to be born. Every day in the uterus is said to be two less days your baby would spend in the hospital at this point. Red blood cell production is done entirely by your baby’s bone marrow. Amniotic fluid is still present and your baby urinates into it daily, about a half a liter of urine a day.
The baby's irises can now dilate and contract in response to light. He or she opens and closes their eyes at will. Even the finger nails reach the end of the fingers. Some babies might even need a nail trim at birth! Your baby may have a lot of hair on their head or none, both extremes are normal.
The weight gain has been fairly incredible recently. Your baby has put on about 2 pounds of weight, mostly fat and muscle tissue, since last month, bringing the total to an average of three pounds eleven ounces (1.7 kilograms), and measurements to 40 cms or 15.8 inches!
Your baby’s organs have been finished forming for a long time. Now is the time for finishing touches. For example, the lungs make final preparations for birth by secreting surfactant to help them expand at birth. Your baby’s kidneys are still producing lots of urine every day, helping to make up the almost two pints of amniotic fluid.
While your baby may be putting on half a pound a week up until about week 37 at which point weight gain slows drastically. The average birth weight is still about seven and a half pounds. Your baby will measure between 18-22 inches at birth.
Your due date is a guess as to when your baby may arrive. The majority of babies will show up from two weeks before this date to two weeks after this date. Labor is caused by the baby’s signals to the mother’s body that he or she is ready to be born. Good luck and good birth!