First of all, congratulations! You are about to enter the most beautiful phase of your life – motherhood. Amidst all the blessings and excitement, if you are anything like me, I am sure a small part of your brain might be wondering when you will experience that first kick from your baby. The firsts are always special whether it is your first or second pregnancy, aren’t they?
Keeping all the excitement in mind, this week-by-week guide to conception timeline will help you get a good idea of what’s going on both inside and outside your body.
You already know that pregnancy is divided into three trimesters until birth. This post briefly describes all the stages of the three trimesters, how fetal development progresses with a week-by-week account.
Get your favorite beverage—a jug of water, a mug of coffee or your favorite snack and settle down. Do bookmark the post or pin it for later reading!
Here we go!
Your week by week guide to pregnancy
The First Trimester – Week 1 to 13
1 week pregnant – This is the first week of pregnancy, but it is not considered as being officially pregnant. Pregnancy is calculated from the first day of the last period and accordingly is the due date announced. This is the time when the body is getting ready for pregnancy – the uterus starts thickening.
2 weeks pregnant – This is the most fertile time of the month. After one conceives, they might notice some light spotting which is not period blood, but a sign that the fertilized egg is attached to the wall of the uterus.
3 weeks pregnant – This is the time when finally, one is pregnant. Egg and sperm have merged into one single cell – a zygote – and fetal development begins, including the development of the brain and spinal cord.
4 weeks pregnant – The real work begins in the fourth week of pregnancy. This is when you’ll probably discover you are pregnant and start having those pregnancy symptoms. Inside you, cells divide to create organs; amniotic sac forms, and the baby is big enough to be spotted in an ultrasound. So exciting!
5 weeks pregnant – In the fourth stage the baby is smaller than a rice grain and appears as a collection of tubes. The first twinges of pregnancy such as morning sickness, urge to urinate and sore breasts start popping up. Time to schedule an appointment with your doc!
6 weeks pregnant – The baby’s vital organs begin to develop. The baby’s heart starts beating by the sixth week while features like eyes and lids start to develop. The digestive system and lungs also start branching out. You will experience nausea, changes in your breasts, heartburn and other symptoms. Talk to your doc about them.
7 weeks pregnant – In the seventh week, the baby’s arms start growing while the body is already forming all the organs. Morning sickness continues for you, but by now your doctor must have prescribed some relief
8 weeks pregnant – There will be no baby bump, but some clear signs like tiredness will be experienced. The baby is now officially a fetus and resembles the size of a bean.
9 weeks pregnant – Your baby is about the size of a grape. The legs are developed, and reproductive organs are beginning to form. The baby may start sucking her thumb. In an ultrasound, you may see the baby move.
10 weeks pregnant – The tail and the webbing between the fingers are gone while the connections have started to form in the brain that will one day help the baby ace a math test. Cool, right? Make sure you exercise to stay healthy.
11 weeks pregnant – The baby is now active and measures two inches. Fingernails and irises start to grow. Just two more weeks until the second trimester and even though you don’t feel the baby move, you can be sure she’s becoming active in her space!
12 weeks pregnant – The twelfth week is officially the end of the first trimester. The risk of miscarriage also drops, and now is a good time to tell others about the pregnancy. As your baby grows, eat healthy so both you and she get all the right nutrients.
13 weeks pregnant – Weight gain starts from this week, and it won’t be long enough when the baby bump also starts showing. You’ll see many changes in your own body, stretch marks and all, and now, your baby begins to develop a unique set of fingerprints!
The Second Trimester – Week 14 to 26
14 weeks pregnant – The conception timeline has now reached the second trimester. The baby is now four inches long and is about the size of a peach. Fingerprints start developing in the fourteenth week. Find out how to bust stress and practice.
15 weeks pregnant – The muscles start getting stronger while the baby starts experimenting with expressions. At this stage, the doctor may conduct quad screening to check for chromosome problems and down syndrome. You’ll find your best sleeping position at this point—because you need a good night’s rest!
16 weeks pregnant – The baby is about five inches long and is the size of an apple. That pregnancy glow starts appearing on your face and your cheeks start looking healthy and flushed. This happens because the blood volume increases for adequate supply to the growing baby, who is ready for a growth spurt.
17 weeks pregnant – The baby’s looks start changing from the seventeenth week onward while the lungs have started to breathe in amniotic fluid. All the organs have started to function properly. Your breasts start growing in preparation to breastfeed the baby. As your abdomen grows, you may experience sciatic nerve pain. Talk to your doctor about it.
18 weeks pregnant – In the eighteenth week of the conception timeline, the baby is about five inches long. The ears have developed to start hearing you and the things around. In the next ultrasound, the baby’s looks can be clearly seen. As your baby bump grows, you’ll need to find time to rest during the day.
19 weeks pregnant – A substance called vernix caseosa now coats the baby instead of amniotic fluid. This waxy coat will be gone before birth – unless the baby is premature. If you feel dizzy, tell your doctor.
20 weeks pregnant – This week marks the half of the pregnancy cycle. 20 weeks from here the baby will be in your arms. Can’t wait, right? By now, the baby measures the size of a small banana. You, time to ensure you’re getting enough iron!
21 weeks pregnant – Tiny tooth buds start popping up, and rapid eye movements may occur. The belly starts showing up, and people start congratulating the mother. This is a great time in your pregnancy.
22 weeks pregnant – The baby is now eight inches long, and the sex organs are also developing. Apart from that, all sorts of systems are also forming inside the baby.
23 weeks pregnant – Now the baby is developed enough to survive outside the womb. The lungs start producing surfactant – it allows them to inflate. The brain has already started to make the connections needed to think. Now is a good time to apply for maternity leave and also explore paternity leave.
24 weeks pregnant – In the twenty-fourth week the baby reaches viability – survival through a ventilator is possible if sudden delivery has to take place. During this week the doctor conducts a glucose screening test to check for gestational diabetes. The baby’s brain is developing rapidly and the lungs are maturing. You will experience heartburn and your skin will show changes.
25 weeks pregnant – The baby is getting bigger with each passing day and is now approximately the size of a broccoli head. A gentle hiccup or two and heartbeat start becoming significant this week onward. The baby also has a gender now.
26 weeks pregnant – This week marks the first time when the baby opens the eyes. The baby reacts with a flurry of movement when someone shines a light on the mother’s abdomen. It’s the end of your second trimester!
The Third Trimester – Week 27 to 40
27 weeks pregnant – Welcome to the third trimester, which is the most crucial part of the conception timeline. The baby has by now developed all the features, but the organs still need some time to mature. The baby also has developed a sleep cycle that may or may not match with the mother and also moves more. Start looking for infant car seats!
28 weeks pregnant – The baby is now as large as squash and can cough, blink, and may even dream. The baby also moves to the birth position.
29 weeks pregnant – The room in the abdomen starts to decrease as the baby starts to grow. During this phase, the mother feels almost every movement of the baby. Make sure you’re eating healthy and getting enough rest.
30 weeks pregnant – This week the baby is about the size of a small chicken. The mother may notice her feet expanding as the joints start to loosen up to prepare for labor. You’ll also feel more tired.
31 weeks pregnant – Baby’s lungs are still developing, and if you go into labor, the baby will need a ventilator for better breathing. You are likely to experience Braxton Hicks contractions and start leaking colostrum.
32 weeks pregnant – The baby is now like a cantaloupe weighing down the mother’s belly. Body hair called lanugo starts falling off leaving hair in the essential parts. Space in the uterus isn’t much but enough for the baby. Are you planning to keep your baby’s cord blood?
33 weeks pregnant – The baby continues to plump, and the bones start to harden. The only bones that are soft are of the skull as it needs to pass seamlessly through the birth canal. There may be a little amniotic fluid leaking.
34 weeks pregnant – By this time the baby is as big as a large pineapple, and most of the organs are developed enough to work on their own. Talk to your doctor about how to prevent an episiotomy.
35 weeks pregnant –The baby is now settling in the pelvis for delivery. Your bladder starts to feel more pressure, and you may spend more time in the bathroom. You’ll also feel a bit breathless and feel the change in your baby’s movements. Start tracking your baby’s kicks.
36 weeks pregnant – Just another month to go. The baby is just about ready for birth. Vernix caseosa is dissolved, and the baby has swallowed it along with other substances. These can be seen in the baby’s first diaper. From now you will see the doctor once a week. Might as well prepare your bag for the hospital!
37 weeks pregnant – The baby is getting bigger, and delivery can happen any day. The immune system of the baby is also arming up, and the head is moving into the pelvis. Your cervix starts to dilate and you may pass your mucus plug.
38 weeks pregnant – The brain of the baby is now controlling the function of her body while the reflexes are also active. You can go into labor any time now. Make sure you rest and enjoy the last few days of pregnancy before you meet your baby!
39 weeks pregnant – The baby is now like a watermelon in your belly. Contractions start more frequently and when they become regular and intense, it is time to visit the doctor.
40 weeks pregnant – Drumroll! This is the week when your baby finally comes out into the world. If delivery doesn’t happen, the doctor may induce labor to make it easy for you.
Final words . . . or perhaps the beginning of a new life!
What a journey! That feeling when the baby is finally in your arms in truly wonderful! Take good care of your baby and your body while pregnant. Don’t skip your appointments with your gynecologist.
I hope this comprehensive conception timeline gave you a fair idea about how your pregnancy progresses. Need more information related to pregnancy and baby care? Explore Momspresso, a digital platform with a panel of experts and suggestions from real mothers from around the world.
Happy and healthy pregnancy to you!
[…] Ask your doctor about a prenatal or sacroiliac belt to stabilize your hips and pelvis. These help a great deal when you start doing weight-bearing exercise especially during the last trimester. […]