Your Second Trimester Journey: Week by Week

Consider the second trimester the midway point of your pregnancy, so halfway to meeting your little one! The second trimester is weeks 13-27, and you may notice a rebound in energy and less morning sickness than the first trimester. During these critical months, your baby has several developmental milestones; everything from skin to the ability to hear. Let’s dive into what you can expect during the second trimester weeks.

What Is the Second Trimester?

The second trimester is the midway point in your pregnancy, taking place between weeks 13 and 27. During the second trimester, your baby is rapidly developing and growing, and many women notice their appetites growing to compensate. Considered the “golden trimester,” you may have fewer symptoms, more energy, vibrant and shiny hair and supple skin during these weeks. That’s due to hormones and the increased blood flow and circulation. 

Physical Changes and Common Symptoms

Your body will likely rapidly transform during the second trimester, and you’ll have some new symptoms with that change.

Physical Transformation

If you haven’t noticed by now, your stomach is probably expanding week over week to accommodate your baby’s growth. Additionally, even now, your body is preparing itself for birth and postpartum. Some of these changes include:

• A growing belly as the uterus expands and your baby grows
• Breast enlargement and possible tenderness, in addition to something called “colostrum,” the first breast milk you’ll produce, which is yellowish in hue
• Skin changes (stretch marks, linea nigra, darkened nipples)
• Weight gain and changes in posture

An Overview of Second Trimester Symptoms

The second trimester is widely regarded as the “easiest” trimester, but that doesn’t mean you won't have some symptoms.

A few include:

• Oral health issues like swollen and painful gums due to hormones
• Backaches from the growing baby and changes in your weight
• Headaches and dizziness
• Heartburn
• Snoring, congestion and nosebleeds, due to changes in your hormones that can cause swelling or irritation in the lining of your nose
• Hemorrhoids, due to the extra blood causing swelling in the veins around the anus

Baby's Development: Week-by-Week Overview

During the second trimester, you and your baby will experience many changes. Let’s review major developmental milestones you can expect over the next few months.

Week 13: Bones and Movement

By week 13, your baby is approximately the size of a peach and can likely move around a lot more.

Additionally: 

• The bones in their skeleton are starting to harden, especially in the skull, legs and arms.
• Their reproductive organs (ovaries or testes) are almost fully developed
• Though the baby may be moving around a lot more, you may not start consistently feel it until week 17.

Week 14: Closer to a Confirmed Sex

By week 14, your baby is approximately the size of a kiwi, and you may be closer to confirming the baby’s sex, though the majority of people will not find out until weeks 18-21.

Additionally:

• Your baby can urinate! They can swallow small amounts of amniotic fluid, which pass back out as urine
• They’re developing vocal cords and have fully developed eyes (though they cannot open them yet!)
• Red blood cells are forming in the spleen

Week 15-17: Eye, Ears and Fingerprints

In week 15, your baby is approximately the size of an apple; by week 17, they’ve grown to about the size of a pomegranate. The ears are rapidly developing during these weeks, and your baby may be able to hear you and even respond to loud noises by week 18.

Other fetal developmental milestones include:

• They can make (entirely random) faces, such as smiling or frowning, and open and close their mouths. However, they do not fully control their facial expressions yet.
• They’re growing a layer of soft, thin, unpigmented hair all over their body called “lanugo.”
• They’re developing eyelashes and eyebrows along with fully-formed eyes, but they cannot open them yet.
• Their skin is developing and thickening. 
• Their nervous system is continuing to develop, so they can start controlling the movement of their arms and legs, including forming a fist.
• The baby’s unique fingerprints are mostly formed by week 17.

Week 18-19: Adult Teeth Already

By week 19, your baby is approximately the size of a large beef tomato. During these weeks:

• Their reflexes are quickly developing; they can move a lot more and control their limbs much better
• They're already developing adult teeth, which are lining up behind their baby teeth
• They can hear more
• The digestive system is rapidly forming.

Week 20: Halfway There

By week 20, your baby is approximately the size and length of a banana, and you are officially halfway through your pregnancy. You are likely feeling the fluttering of small kicks and movement as the baby becomes more active every day; this is called “quickening.”

Additionally:

• You can distinguish their genitals with an ultrasound
• The baby is regularly sleeping and waking up
• A white, greasy layer called a “vernix” forms around your baby’s delicate skin. The vernix also helps the baby’s journey down the birth canal.

Week 21-24: Breathing Practice

By week 24, your baby is approximately the size of a corn on the cob. Additionally:

• The baby’s head, arms, legs and body are all in proportion
• Their kicks and punches get much more noticeable, and you’ll probably notice your stomach moving
• By week 24, they may be able to open and close their eyes
• Their lungs make breathing movements, though they cannot function independently
• The baby has in-utero bowel movements

Week 25-27: Preparing for the Final Trimester

These are the final few weeks of the third trimester, and your baby’s organs are all maturing as they prepare for life outside the womb. By week 27, your baby is approximately the size of a head of cauliflower or cabbage. They are gaining weight, and their skin will go from thin and wrinkly to the supple and soft plump skin we’re used to in newborns.

Nutrition 

During your second trimester, your baby is growing and developing very fast, and they’re relying solely on you to deliver the nutrients they need. If you aren’t eating properly or taking your prenatal vitamins and supplements, you run the risk of nutritional depletion. Here are some nutrients that can support you this (and every) trimester:

• Folate, Choline and B12: Continue getting these nutrients to support processes like DNA Synthesis and the baby’s brain development.
• Vitamin D, Vitamin K2, Magnesium, and Calcium: Support your healthy bones and teeth, as well as your baby's bone development.
• Omega-3s: Support the baby's brain, nerve, and eye development. They also support mood and heart health.

Ensure you’re eating a balanced diet with a variety of fruits, vegetables, healthy fats, protein, and whole grains. You may experience constipation during pregnancy, so adding high-fiber foods like beans, whole grains, and apples may help a sluggish bowel system. 

Commit to a comprehensive, high-quality prenatal vitamin like the Needed Prenatal Multi. The formula contains optimal levels of 26 nutrients supporting your and your baby’s health and wellness during the 2nd trimester and beyond. 

Avoid raw meat, fish, and eggs– as well as alcohol, caffeine and processed deli meats. 

Prenatal Fitness

Is it ok to exercise while pregnant? Yes, it is safe and recommended! In a healthy, normal pregnancy, you can continue your regular workout routine or even start some physical activity. You should aim for at least 150 minutes of moderate activity each week during pregnancy. That will depend on your current fitness level and what your healthcare provider says,

Pregnancy-Safe Workouts

Depending on your pre-pregnancy fitness level and the direction from your healthcare provider, any exercise you did before pregnancy, you can likely continue into your second trimester. If you want to try something low-impact or you’re looking to start working out, you can try:

• Yoga and pilates
• Stretching with a pregnancy ball
• Water aerobics 
• Walking or light jogging

Exercising while pregnant has tremendous health benefits. It’s been shown to reduce the risk of preeclampsia, gestational diabetes, urinary incontinence, and pelvic and lower back pain.

Flying During Pregnancy

As your stomach grows, you may hear dissenting opinions on how safe it is to fly during pregnancy. In a healthy, normal pregnancy, experts agree that the second trimester (weeks 14-28) is the best time to fly, since you're likely have fewer symptoms and more energy. However, you can fly domestically up to 36 weeks pregnant. Consult your healthcare provider and the airline if you plan to fly over longer distances.

 Prenatal Care and Medical Appointments

During the second trimester, ongoing prenatal care is essential to monitor your health and the baby’s development. You can expect to have one prenatal appointment every four weeks, and during those appointments, your prenatal care provider, such as your OB/GYN or midwife will:

• Record your vitals (blood pressure, weight, heart rate, size of your stomach, etc.)
• Monitor the baby’s fundal height by measuring the distance from your pubic bone to the top of your uterus—this helps track the baby’s growth.
• Check the fetal heartbeat using a Doppler device, a handheld tool that monitors blood flow in your baby’s heart and turns that into a sound.

There are also several screenings and tests that take place during the second trimester.

Second Trimester Pregnancy Screenings

Your prenatal appointments may include several tests and screenings, including some optional genetic tests. 

Pregnancy Multiple Markers Test

The multiple markers test (maternal serum screening) is a blood test between 15 and 21 weeks of pregnancy. It measures substances in the mother’s blood (alphafetoprotein/AFP and human chorionic gonadotropin/hCG) to assess the risk of certain congenital disabilities or genetic conditions in the fetus, such as:

• Down syndrome 
• Trisomy 18 or other chromosomal abnormalities
• Neural tube defects, such as spina bifida
• Defects in the abdominal wall of the fetus
• A miscalculated due date

Fetal Ultrasound

A fetal ultrasound is an imaging test that uses sound waves to create images of the baby. In the second trimester, as your baby develops, the ultrasound can convey more information about the baby, including the baby’s sex.

Second Trimester FAQs

When does the second trimester start? Is it week 13 or 14?

The second trimester typically starts at week 13.

When does the second trimester end?

The second trimester ends at week 27, covering the third, fourth and fifth months of pregnancy.

Can you fly while pregnant?

Yes, you can fly while pregnant. Experts agree that the second trimester is the best time to fly since pregnant women typically feel best during weeks 13-27. In a healthy, low-risk pregnancy, you can fly domestically until 36 weeks. After that, you will likely need a sign-off from your OB/GYN. 

What should I expect during the second trimester?

During the second trimester, many people have fewer symptoms, such as morning sickness and fatigue, and some people refer to this as the “golden trimester.” However, you may have other symptoms like:

• Increased appetite
• Swollen or bleeding gums
• Backaches
• Headaches and dizziness
• Heartburn
• Snoring, congestion and nosebleeds
• Hemorrhoids

Can you run while pregnant?

You can run and jog during pregnancy, depending on your pre-pregnancy health and fitness level and your healthcare providers’ guidance.

When do babies get eyebrows?

Babies develop eyebrows around weeks 17-20.

When are a baby’s fingerprints formed?

A baby’s fingertips, including their unique fingerprints, start to form around week 13, and by week 17, the patterns are set.

When do a baby's ears develop?

The baby’s ears begin to develop as early as 5 weeks, when the inner ear structures start to form. During weeks 16-20, the ears are fully developed, and the baby can hear a wide range of sounds.