Welcome to the incredible journey of pregnancy! If you’re a dad-to-be, this is your go-to guide for understanding what’s happening week by week. We’ve got you covered from the first signs to the big day. We’ll explore the changes your partner is experiencing, how your baby is growing (with some cool size comparisons), and practical tips on how you can be the best support. This is not an extensive look into pregnancy or trimesters. We have an article on that, which we highly recommend reading. Let’s dive into this journey together and make these nine months a memorable and supportive experience for both of you!
Related Article: Pregnancy & Trimesters Explained
In this article:
First Trimester (Weeks 1-12)
Month 1
Week 1 & 2
- Mom’s Experience: These weeks involve the menstrual period and ovulation. There’s no pregnancy yet, but it’s a crucial time for maintaining a healthy lifestyle.
- Dad’s Support: Encourage and participate in healthy habits together, like eating well and reducing stress, which can help prepare for pregnancy.
- Baby’s Size: No baby yet.
Week 3
- Mom’s Experience: Fertilization may occur. She won’t likely notice any physical changes, but maintaining a healthy environment is critical.
- Dad’s Support: Continue supporting healthy lifestyle choices and be understanding of any emotional changes, even if they’re subtle at this stage.
- Baby’s Size: Comparable to a poppy seed or a grain of sand, about 0.04 inches.
- Development: The fertilized egg divides and starts to implant.
Week 4
- Mom’s Experience: She might notice early signs like a missed period, slight fatigue, or breast tenderness. These changes can be exciting, but also terrifying. This is where pregnancy tests start to show positive, with the help of Human Chorionic Gonadotropin (hCG).
- Dad’s Support: Be supportive by acknowledging the changes and offering comfort. It’s an excellent time to discuss scheduling a doctor’s appointment.
- Baby’s Size: The size of a sesame seed is approximately 0.08 inches.
- Development: The placenta and amniotic sac are forming; facial features begin to develop.
Month 2
Week 5
- Mom’s Experience: She may start experiencing morning sickness, fatigue, and frequent urination. These symptoms can be quite uncomfortable and sometimes overwhelming.
- Dad’s Support: Offer empathy and practical support, like preparing small, frequent meals to help with nausea. Accompany her to any doctor appointments for emotional support.
- Baby’s Size: About the same size as the tip of a pencil, approximately 0.13 inches.
- Development: The baby’s heart begins to beat. Tiny buds for arms and legs start forming.
Week 6
- Mom’s Experience: Symptoms like nausea and fatigue often become more pronounced. This can be a challenging time emotionally and physically.
- Dad’s Support: Be patient and understanding. Help with household chores to reduce her stress and encourage her to rest when needed.
- Baby’s Size: Roughly the size of a paper clip, around 0.2 inches.
- Development: Facial features, brain, and muscles are developing.
Week 7
- Mom’s Experience: Increased saliva, heartburn, or bloating may occur. These symptoms can be unexpected and sometimes embarrassing to discuss.
- Dad’s Support: Be a good listener and provide reassurance. Assisting with dietary changes can help alleviate some of these symptoms.
- Baby’s Size: About the size of a wireless earbud, approximately 0.3 inches.
- Development: The baby’s brain continues to develop. The umbilical cord appears.
Week 8
- Mom’s Experience: Breast tenderness and possible weight gain or bloating are common during this stage of pregnancy. She might start to feel more emotionally connected to the pregnancy, which great for her mental and physical health.
- Dad’s Support: Express excitement and interest in the pregnancy progress. Help create a comfortable environment at home.
- Baby’s Size: Now the size of a LEGO brick, around 0.6 inches.
- Development: Fingers and toes are starting to form. The baby’s bones begin to harden.
Month 3
Week 9
- Mom’s Experience: Morning sickness might peak around this time, potentially affecting her daily routine. Fatigue and frequent urination continue.
- Dad’s Support: Be understanding of the physical and emotional toll. Help by taking on more responsibilities at home and being patient with her fluctuating mood.
- Baby’s Size: Comparable to a cherry, about 0.9 inches.
- Development: Essential body parts are formed; the baby begins to move.
Week 10
- Mom’s Experience: Some of the rough pregnancy symptoms may start to lessen, offering a bit of relief. The waistline might begin to thicken, marking a visible change in her body.
- Dad’s Support: Celebrate the small milestones and the decrease in symptoms. Engage in gentle activities together, like walking, which can be beneficial for her health.
- Baby’s Size: The size of a bottle cap, roughly 1.2 inches.
- Development: Vital organs are functioning; the baby starts to swallow and kick.
Week 11
- Mom’s Experience: A decrease in symptoms like nausea is common, and she might feel a surge in energy levels. This can be a more comfortable period.
- Dad’s Support: Encourage her to use this energy positively but remind her not to overdo it. Plan for upcoming prenatal appointments and discuss any concerns or questions she might have.
- Baby’s Size: About the size of a USB flash drive, approximately 1.6 inches.
- Development: The baby is almost fully formed. Fingers and toes separate; hair follicles and nail beds form.
Week 12
- Mom’s Experience: The risk of miscarriage drops significantly, which can be a huge relief. She may start showing a tiny baby bump, marking a new stage in her pregnancy journey.
- Dad’s Support: Celebrate this milestone and offer reassurance about her changing body and the excitement of being parents. Discuss and plan for the future, like the nursery or baby care essentials.
- Baby’s Size: Comparable to a AA battery, around 2 inches.
- Development: The baby’s reflexes are developing. It can open and close fingers and start to make sucking movements.
Second Trimester (Weeks 13-27)
Month 4
Week 13
- Mom’s Experience: She may notice a significant decrease in early pregnancy symptoms and an increase in energy. The baby bump becomes more noticeable.
- Dad’s Support: Acknowledge the visible changes and continue to provide emotional support. It’s an excellent time to start discussing maternity wear and comfort to aid in her pregnancy journey.
- Baby’s Size: Similar to a matchbox, about 2.9 inches.
- Development: The baby has fingerprints, and the veins and organs are clearly visible through the skin.
Week 14
- Mom’s Experience: This is often a more comfortable week. She might feel more like herself with a noticeable decrease in nausea.
- Dad’s Support: Encourage her to stay active and healthy. This is a great time for both parents to start a gentle exercise routine together.
- Baby’s Size: Comparable to a golf ball, around 3.4 inches.
- Development: The baby’s facial muscles are developing, and it might even be sucking its thumb.
Week 15
- Mom’s Experience: She may start to feel the baby’s movements, which can be exciting. Appetite might increase.
- Dad’s Support: Share in the excitement of feeling the baby move. Help prepare healthy snacks and meals to satisfy her growing appetite.
- Baby’s Size: About the size of a computer mouse, approximately 4 inches.
- Development: The baby is moving fluidly; bones are getting stronger.
Week 16
- Mom’s Experience: The increased blood volume might cause occasional dizziness. The baby bump is more visible, and she might feel more confident.
- Dad’s Support: Be there to offer a hand or support when she feels dizzy. Compliment her on her appearance and the growing baby bump.
- Baby’s Size: Similar to a typical smartphone, around 4.5 inches.
- Development: The baby’s eyes can move, and the ears are in their final position.
Month 5
Week 17
- Mom’s Experience: She might begin to feel more frequent movements from the baby. Some women also start to experience swelling in their hands and feet.
- Dad’s Support: Encourage her to rest with her feet up to reduce swelling. Sharing the excitement of baby movements can be a bonding experience.
- Baby’s Size: Comparable to a game controller, around 5 inches.
- Development: Fat stores begin to develop, and the baby starts to hear.
Week 18
- Mom’s Experience: The uterus is growing, which may cause some aches and pains. She may also begin to feel the baby’s kicks more distinctly.
- Dad’s Support: Offer massages for aches and pains. Talk and sing to the baby – it can hear you now!
- Baby’s Size: Similar to a TV remote, about 5.6 inches.
- Development: The nervous system is maturing, and the baby can yawn, hiccup, and swallow.
Week 19
- Mom’s Experience: She might experience lower abdominal aches as the baby grows. Some women have trouble sleeping due to the baby’s increased activity.
- Dad’s Support: Assist in finding comfortable sleeping positions, perhaps with the help of pregnancy pillows. Be understanding of her sleep difficulties.
- Baby’s Size: About the size of a dollar bill, around 6 inches.
- Development: Protective vernix caseosa, a waxy coating, covers the baby. Sensory development continues.
Week 20
- Mom’s Experience: This marks the halfway point of the pregnancy. She might have an anatomy scan ultrasound, which is an exciting and emotional moment.
- Dad’s Support: Attend the ultrasound appointment if possible. It’s a great opportunity to see the baby together and discuss any findings with the healthcare provider.
- Baby’s Size: Similar to a banana, around 6.5 inches.
- Development: The baby is more active, and the mother may begin to feel stronger movements. The skin is forming unique fingerprints.
Month 6
Week 21
- Mom’s Experience: She might start to feel Braxton Hicks contractions, which are like practice contractions. Her appetite may continue to increase.
- Dad’s Support: Help her stay hydrated and comfortable. Learn about Braxton Hicks contractions together to understand what’s normal.
- Baby’s Size: Comparable to a water bottle, around 10.5 inches (head to toe).
- Development: The baby is sleeping and waking at regular intervals. Taste buds are fully developed.
Week 22
- Mom’s Experience: Increased fetal movements can be more noticeable. She may also start to feel more physically strained due to the growing belly.
- Dad’s Support: Be understanding of her discomfort. Help with tasks that are becoming more difficult for her to manage.
- Baby’s Size: Similar to a small football, about 11 inches.
- Development: The baby’s eyes are formed, though the irises still lack pigment.
Week 23
- Mom’s Experience: The increased belly size may cause backaches and discomfort. She may also experience changes in skin pigmentation.
- Dad’s Support: Offer back massages and help her maintain a good posture. Be supportive of any skin changes she might be self-conscious about.
- Baby’s Size: About the size of a typical book, around 11.4 inches.
- Development: The baby starts to develop a regular sleep-wake cycle.
Week 24
- Mom’s Experience: She might experience some shortness of breath as the uterus expands upwards. The baby’s movements are more pronounced and can even be visible from the outside.
- Dad’s Support: Help her find comfortable positions to alleviate shortness of breath. Enjoy watching and feeling the baby’s movements together.
- Baby’s Size: Comparable to a ruler, obviously, around 12 inches.
- Development: The baby’s brain development is rapid. Lungs are developing but not yet fully mature.
Month 7
Week 25
- Mom’s Experience: She may start experiencing more swelling in her ankles and feet. There’s also an increase in blood supply, which can lead to visible veins.
- Dad’s Support: Encourage her to rest with her feet elevated and stay hydrated. Be reassuring about the physical changes and offer help with comfortable clothing choices.
- Baby’s Size: Comparable to a rutabaga, around 13.6 inches.
- Development: The baby is growing more hair, and its skin is becoming less translucent.
Week 26
- Mom’s Experience: She might feel Braxton Hicks contractions more frequently. Difficulty sleeping due to the baby’s size and movements is common.
- Dad’s Support: Help create a comfortable sleeping environment. Understand that her sleep patterns may change and offer support during restless nights.
- Baby’s Size: Similar to a laptop keyboard, about 14 inches.
- Development: The baby’s eyes begin to open, and it starts to respond to sounds and light.
Week 27
- Mom’s Experience: Balance and coordination might be more challenging due to her changing center of gravity. She might also experience heartburn and indigestion.
- Dad’s Support: Assist with tasks that require bending or reaching. Be supportive of dietary adjustments to ease heartburn.
- Baby’s Size: About the size of a head of cauliflower, around 14.4 inches.
Third Trimester (Weeks 28-40)
Week 28
- Mom’s Experience: This marks the beginning of the third trimester. She may feel more tired and experience shortness of breath as the baby grows.
- Dad’s Support: Encourage rest and relaxation. This is a good time to start discussing the birth plan and final preparations.
- Baby’s Size: Comparable to a standard loaf of bread, around 14.8 inches.
- Development: The baby’s eyes can blink, and it has eyelashes. The baby is adding fat and continuing to mature.
Month 8
Week 29
- Mom’s Experience: She may feel more fatigued and have difficulty finding a comfortable sleeping position. The belly is quite large now, making movements more cumbersome.
- Dad’s Support: Help make her comfortable, especially at night. Offer to run errands and take on more household tasks.
- Baby’s Size: Comparable to a butternut squash, about 15.2 inches.
- Development: The baby’s muscles and lungs are continuing to mature. It’s becoming cramped inside the uterus.
Week 30
- Mom’s Experience: Braxton Hicks contractions may become more frequent. She might experience more backaches and leg cramps.
- Dad’s Support: Assist with gentle stretching exercises for leg cramps. Be understanding and patient, especially when she’s experiencing discomfort.
- Baby’s Size: Similar to a large cabbage, about 15.7 inches.
- Development: The baby’s brain is developing quickly. It can turn its head and make facial expressions.
Week 31
- Mom’s Experience: As the baby grows, she might have more pronounced shortness of breath and frequent urination. Her belly is very prominent now.
- Dad’s Support: Accompany her on short walks, which can help with her breathing. Be empathetic to her increasing discomfort and need for frequent restroom breaks.
- Baby’s Size: About the size of bowling ball, around 16.2 inches.
- Development: The baby is gaining weight rapidly. Its five senses are now fully developed.
Week 32
- Mom’s Experience: She may start feeling the urge to “nest” and prepare for the baby’s arrival. Physical discomfort from the baby’s size can increase.
- Dad’s Support: Help with nesting activities, like setting up the nursery. Ensure she’s comfortable, and encourage her to rest when needed.
- Baby’s Size: Comparable to a typical men’s shoebox, around 16.7 inches.
- Development: The baby’s bones are fully formed, but the skull remains soft for birth. It’s practicing breathing.
Week 33
- Mom’s Experience: She may feel increased discomfort due to the baby’s size and position. Difficulty sleeping and frequent bathroom visits are common.
- Dad’s Support: Help her find comfortable sleeping positions, perhaps with extra pillows. Be patient and understanding with her discomfort and restlessness.
- Baby’s Size: Comparable to a pineapple, about 17.2 inches.
- Development: The baby’s bones are hardening, except for the skull. It’s also starting to descend into the birthing position.
Week 34
- Mom’s Experience: Braxton Hicks contractions can become stronger. She might feel more anxious or excited as the due date approaches.
- Dad’s Support: Attend childbirth classes together if possible. Offer reassurance and support as she expresses any fears or anxieties about labor and delivery.
- Baby’s Size: Similar to a cantaloupe, around 17.7 inches.
- Development: The baby’s fat layers are continuing to form, which will help regulate temperature after birth.
Month 9
Week 35
- Mom’s Experience: She may notice swelling in her ankles and feet. The increased size of the baby can lead to more pronounced discomfort and shortness of breath.
- Dad’s Support: Encourage her to rest with her feet elevated. Assist with daily tasks that are now more challenging for her.
- Baby’s Size: About the size of a honeydew melon, around 18.2 inches.
- Development: The baby’s kidneys are fully developed, and the liver can process waste products.
Week 36
- Mom’s Experience: She might feel the baby “dropping” lower into the pelvis, preparing for birth. This can cause increased pressure in the lower abdomen.
- Dad’s Support: Help with any last-minute preparations for the baby’s arrival. Offer emotional support, as she might feel a mix of excitement and nervousness.
- Baby’s Size: Comparable to a head of romaine lettuce, around 18.7 inches.
- Development: The baby’s skin is getting smooth and soft. The lungs are nearly fully developed.
Week 37
- Mom’s Experience: Full-term is reached! She might feel more comfortable as the baby drops lower. Increased pressure on the bladder leads to frequent urination.
- Dad’s Support: Help ensure the hospital bag is packed and ready. Be supportive and patient, especially as she may become more anxious about labor signs.
- Baby’s Size: Comparable to a two-liter soda, around 19.1 inches.
- Development: The baby is considered full-term. Most of its systems are fully developed and ready for the outside world.
Week 38
- Mom’s Experience: She may experience more Braxton Hicks contractions and possibly some pelvic discomfort as the baby settles into the birth position.
- Dad’s Support: Stay alert for any signs of labor and be ready to act. Offer emotional support and reassurance as anticipation for labor increases.
- Baby’s Size: Similar to a leek, about 19.6 inches.
- Development: The baby continues to build a layer of fat to help control body temperature after birth.
Week 39
- Mom’s Experience: The waiting game intensifies. She might feel a combination of excitement and nervousness. Sleep might be difficult.
- Dad’s Support: Be ready for the hospital trip at any moment. Keep her company during sleepless nights and help keep her comfortable and relaxed.
- Baby’s Size: About the size of a small watermelon, around 20 inches.
- Development: The baby’s brain and lungs are still maturing, although they are nearly ready for birth.
Week 40
- Mom’s Experience: The official due date arrives, but it’s common for pregnancies to go slightly over. She may feel eager, impatient, or anxious.
- Dad’s Support: Provide constant emotional support. Help distract her from the waiting with light activities or relaxation techniques.
- Baby’s Size: Comparable to a small pumpkin, about 20.2 inches.
- Development: The baby is fully developed and ready for birth. It might move less due to the tight space.
For more information on pregnancy and trimesters, check out our in-depth article, here. For advice for new dads, be sure to give this article a quick read.
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