16 Weeks Pregnant: Baby Development & What to Expect

What Does My Baby Look Like at 16 Weeks?

At 16 weeks pregnant, your baby measures approximately 12 centimeters (4.7 inches) from crown to rump and weighs around 100 grams (3.5 ounces). The skeleton is becoming harder as cartilage turns to bone, the nervous system is functioning with more coordinated movements, and your baby can now hear sounds both inside and outside your body.

Week 16 marks an exciting time in your baby's development. By now, your baby has grown significantly from the tiny embryo of the first trimester into a clearly recognizable human form. The body is becoming more proportional, with the head no longer appearing so large compared to the rest of the body.

One of the most remarkable developments at this stage is the maturation of the nervous system. The neural connections are forming rapidly, allowing your baby to make more coordinated movements. If you have an ultrasound scan, you may see your baby moving their arms and legs, making facial expressions, or even sucking their thumb. These movements are becoming less jerky and more purposeful as the nervous system develops.

The skeleton, which was previously made entirely of cartilage, is now undergoing ossification - the process of hardening into bone. This transformation begins in the center of each bone and gradually spreads outward. Calcium and other minerals are being deposited to strengthen your baby's developing bones, which is why adequate calcium intake during pregnancy is so important.

Baby's Hearing Development

Perhaps one of the most exciting developments at 16 weeks is that your baby can now hear sounds. The structures of the inner ear have developed sufficiently to detect sound waves, and your baby may startle or jump if there's a sudden loud noise near your belly.

However, the sound environment inside your womb is naturally muffled and protective. Imagine lying in a bathtub with your ears underwater - that's similar to what sound levels are like for your baby. This natural dampening protects your baby's developing ears from potentially harmful noise levels.

Your baby constantly hears the sounds of your body: the rhythmic beating of your heart, the whoosh of blood flowing through your vessels, and the gurgles of your digestive system. These sounds are comforting and familiar, which is why newborn babies are often soothed by recordings of heartbeat sounds or white noise.

Other Developments This Week

Your baby's facial features are becoming more defined during week 16. The eyes, which were on the sides of the head, have moved to the front of the face. The ears have moved to their final position on the sides of the head. Eyebrows and eyelashes are beginning to grow, and the eyes can make slow side-to-side movements, though the eyelids remain fused shut.

Inside your baby's body, the circulatory system is working efficiently. The heart beats approximately 150 times per minute and pumps about 25 quarts of blood each day. The digestive system is also developing, with your baby beginning to swallow amniotic fluid and pass it through their kidneys, producing small amounts of urine.

What Symptoms Are Normal at 16 Weeks Pregnant?

At 16 weeks pregnant, common symptoms include a growing belly, increased energy, reduced morning sickness, pelvic girdle pain, round ligament pain, nasal congestion, and mild backache. Some women may begin to feel the first fetal movements (quickening), though this is more common between weeks 18-22 for first pregnancies.

The second trimester is often called the "honeymoon period" of pregnancy, and week 16 is right in the heart of this more comfortable phase. Many women find that the challenging symptoms of early pregnancy begin to subside, replaced by a sense of renewed energy and wellbeing.

Your body is adapting remarkably well to supporting your growing baby. The nausea and fatigue that may have dominated your first trimester are typically easing now, allowing you to enjoy your pregnancy more fully. However, new symptoms may emerge as your body continues to change.

Growing Belly and Weight Changes

By week 16, your uterus has grown to approximately the size of a small melon. The fundus (the top of the uterus) can now be felt about halfway between your pubic bone and navel when you lie flat. Your pregnancy bump is likely becoming more noticeable, especially to those who know you're expecting.

Weight gain typically accelerates during the second trimester. Most healthcare providers recommend gaining about 0.5 to 1 pound per week during this time, though this can vary based on your pre-pregnancy weight and individual circumstances. By week 16, total weight gain is usually between 5 to 10 pounds, though this varies considerably from woman to woman.

Pelvic Girdle Pain

Pelvic girdle pain (PGP), also known as symphysis pubis dysfunction (SPD), affects up to 20% of pregnant women and often becomes noticeable around this stage of pregnancy. This condition occurs because pregnancy hormones, particularly relaxin, cause the ligaments and joints in your pelvis to become more flexible in preparation for childbirth.

While this increased flexibility is beneficial for delivery, it can cause pain and discomfort in the pelvis, lower back, groin, hips, buttocks, back of the thighs, and the pubic bone. The pain may be worse when walking, climbing stairs, turning over in bed, or standing on one leg.

Round Ligament Pain

Round ligament pain is another common symptom around week 16. The round ligaments, which support your uterus, are stretching as your baby grows. This stretching can cause sharp, stabbing pains or a dull ache in the lower abdomen or groin area, particularly on the right side.

Round ligament pain is typically triggered by sudden movements such as standing up quickly, coughing, sneezing, or rolling over in bed. While uncomfortable, it's generally harmless and a normal part of pregnancy. Resting, moving slowly, and applying gentle heat can help relieve the discomfort.

Nasal Congestion and Nosebleeds

Many pregnant women experience nasal congestion during the second trimester, sometimes called "pregnancy rhinitis." Increased blood volume and hormonal changes can cause the mucous membranes in your nose to swell, making you feel stuffed up. Some women also experience more frequent nosebleeds due to the increased blood supply to the nasal passages.

Using a humidifier, saline nasal spray, and staying well-hydrated can help manage these symptoms. Avoid using decongestant medications without first consulting your healthcare provider.

Feeling Baby Move (Quickening)

Some women begin to feel their baby's movements around week 16, though this is more common between weeks 18-22, especially for first pregnancies. These early movements, called "quickening," are often described as flutters, bubbles, or a gentle tapping sensation. They may initially be mistaken for gas or muscle twitches.

If this is your second or subsequent pregnancy, you may recognize fetal movements earlier because you know what to expect. The position of your placenta can also affect when you feel movement - an anterior (front-facing) placenta may cushion the movements, making them harder to detect early on.

When Will I Have My Ultrasound Scan?

Most pregnant women are offered a mid-pregnancy ultrasound scan between weeks 18-22. Around week 16, you may receive your appointment notification. This detailed anatomy scan checks your baby's development, confirms the due date, examines the placenta position, and can often determine the baby's sex if you wish to know.

By week 16, many expectant parents have received or are about to receive an appointment for their mid-pregnancy ultrasound scan. This detailed examination, also known as the anomaly scan or anatomy scan, is typically performed between 18 and 22 weeks of pregnancy and is one of the most comprehensive checks of your baby's development.

The timing of ultrasound scans can vary depending on your healthcare system and individual circumstances. Some providers offer an earlier dating scan between weeks 8-14 to confirm the pregnancy and estimate the due date. Others may offer a nuchal translucency scan between weeks 11-14 as part of screening for chromosomal abnormalities.

What the Anatomy Scan Checks

The mid-pregnancy anatomy scan is a thorough examination that checks many aspects of your baby's development. The sonographer will examine your baby's head and brain, face (checking for cleft lip), spine, heart and major blood vessels, stomach, kidneys, bladder, arms and legs, and the umbilical cord. They'll also check your placenta's position and your amniotic fluid levels.

This scan can detect various structural abnormalities, though it's important to understand that not all conditions can be identified through ultrasound. The detection rate varies depending on the specific condition and factors such as the baby's position, mother's body type, and the quality of the ultrasound equipment.

Finding Out the Baby's Sex

If you wish to know your baby's sex, this information can often be determined at the mid-pregnancy scan, though accuracy depends on the baby's position and the clarity of the image. If you prefer not to know, inform the sonographer at the start of your appointment.

Some healthcare providers have policies about revealing the baby's sex, and accuracy can vary. The sex is typically more reliably determined at the anatomy scan (18-22 weeks) than at earlier scans.

What Vaccinations Are Recommended During Pregnancy?

Several vaccinations are recommended during pregnancy to protect both mother and baby. The whooping cough (pertussis) vaccine is recommended from week 16 onwards. Influenza vaccine is recommended during flu season, and COVID-19 vaccination is recommended after week 12. These vaccines help protect your baby, who cannot be vaccinated until after birth.

Vaccinations during pregnancy play a crucial role in protecting both you and your baby. When you receive certain vaccines while pregnant, you pass protective antibodies to your baby through the placenta. This provides important protection during the first few months of life, before your baby is old enough to receive their own vaccinations.

The safety of recommended vaccines during pregnancy is well-established through extensive research. Vaccination does not increase the risk of miscarriage, birth defects, or other pregnancy complications. In fact, many infections are more dangerous during pregnancy, making vaccination especially important.

Whooping Cough (Pertussis) Vaccination

Whooping cough is a highly contagious respiratory infection that can be life-threatening for young babies. Because infants cannot receive their first pertussis vaccine until they are 2 months old, they rely on maternal antibodies for protection during their first weeks of life.

The pertussis vaccine (given as part of the Tdap vaccine) is recommended from week 16 of pregnancy onwards. The ideal timing is between weeks 16 and 32, as this allows maximum time for antibodies to develop and transfer to your baby. However, the vaccine can be given at any time during pregnancy if needed.

Vaccination during each pregnancy is recommended, even if you were vaccinated during a previous pregnancy or have received the vaccine as an adult. Antibody levels decrease over time, and vaccination during pregnancy ensures your baby receives the highest possible level of protection.

Influenza Vaccination

Pregnant women are more susceptible to severe complications from influenza due to changes in the immune system, heart, and lungs during pregnancy. Influenza infection during pregnancy has been associated with increased risks of hospitalization, preterm birth, and other complications.

The flu vaccine is recommended for all pregnant women during flu season, regardless of the stage of pregnancy. The vaccine protects both you and your baby, as maternal antibodies pass through the placenta and provide protection for the first few months after birth.

COVID-19 Vaccination

COVID-19 vaccination is recommended for pregnant women after the first trimester (after week 12). Pregnant women with COVID-19 are at increased risk of severe illness, ICU admission, and preterm birth. Vaccination significantly reduces these risks.

Studies have shown that COVID-19 vaccines are safe and effective during pregnancy. Like other vaccines given during pregnancy, they also provide some protection to newborns through transferred antibodies.

How Can I Protect My Baby from Harmful Chemicals?

Many chemicals can cross the placenta and potentially affect your baby's development. To minimize exposure, avoid unnecessary chemicals, choose fragrance-free products, ensure good ventilation when using cleaning products, wear gloves for cleaning, avoid pesticides, and don't heat food in plastic containers. Always read product labels and choose safer alternatives when possible.

During pregnancy, your baby is developing rapidly, and their organs and systems are particularly sensitive to environmental factors. Many chemicals can cross the placenta and reach your baby, which is why reducing exposure to potentially harmful substances is an important part of prenatal care.

While it's impossible to avoid all chemical exposures, making informed choices can significantly reduce potential risks. The good news is that most everyday exposures at normal levels are unlikely to cause harm. However, taking reasonable precautions can provide additional peace of mind.

Common Sources of Chemical Exposure

Household cleaning products often contain chemicals that may be best avoided during pregnancy. When using cleaning products, ensure good ventilation by opening windows, wear gloves to prevent skin absorption, and consider switching to safer, fragrance-free alternatives. Many effective cleaning products are now available that are specifically formulated to be safer during pregnancy.

Personal care products such as cosmetics, lotions, and hair dyes can also contain chemicals of concern. Look for products labeled as fragrance-free and paraben-free. While occasional use of hair dye is generally considered safe during pregnancy, you may want to wait until after the first trimester and ensure good ventilation during application.

Food-Related Precautions

Some chemicals can enter your body through food. Avoid heating food in plastic containers, as heat can cause chemicals to leach into food. Use glass or ceramic containers instead. Wash fruits and vegetables thoroughly to remove pesticide residues, and consider choosing organic options when possible, especially for items on the "dirty dozen" list.

Limit consumption of large predatory fish such as shark, swordfish, king mackerel, and tilefish, which can contain high levels of mercury. Instead, choose lower-mercury options like salmon, sardines, and anchovies, which also provide beneficial omega-3 fatty acids.

Environmental Considerations

At home, ensure your living space is well-ventilated. If you're renovating or painting, leave these tasks to others if possible, or ensure excellent ventilation and use low-VOC (volatile organic compound) products. Avoid using pesticides indoors, and if pest control is necessary, choose less toxic options or hire a professional who uses pregnancy-safe methods.

At work, if you're exposed to chemicals as part of your job, speak with your employer about your pregnancy. You may be entitled to workplace accommodations or reassignment to safer duties. Your healthcare provider can provide documentation if needed.

Why Do I Have Pain in My Pelvis?

Pelvic pain during pregnancy, called pelvic girdle pain (PGP), affects up to 20% of pregnant women. It occurs because pregnancy hormones like relaxin make joints more flexible, causing pain in the pelvis, lower back, groin, hips, buttocks, and pubic bone. Treatment includes physiotherapy, support belts, and modified activities. Contact your healthcare provider if pain significantly affects daily activities.

Pelvic girdle pain is one of the most common musculoskeletal complaints during pregnancy, and many women first notice it around the second trimester. Understanding why this pain occurs and how to manage it can help you stay comfortable as your pregnancy progresses.

The hormone relaxin, which increases during pregnancy, plays a crucial role in preparing your body for childbirth by making your ligaments and joints more flexible. However, this increased flexibility can cause instability in the pelvic joints, leading to pain and discomfort. The symphysis pubis (the joint at the front of your pelvis) and the sacroiliac joints (at the back of your pelvis) are particularly affected.

Symptoms of Pelvic Girdle Pain

PGP can cause pain in several areas: the front of the pelvis over the pubic bone, the lower back and buttocks, the groin and inner thighs, the hips, and sometimes pain that radiates down the legs. The pain is typically worse with activities that involve moving one leg at a time, such as walking, climbing stairs, getting dressed, or turning over in bed.

Some women experience a clicking or grinding sensation in the pelvis. The severity can range from mild discomfort to significant pain that affects daily activities. PGP does not harm your baby and does not affect your ability to have a vaginal delivery, though it may influence your preferred positions during labor.

Managing Pelvic Girdle Pain

Several strategies can help manage PGP effectively. Physiotherapy is often the most helpful intervention, with a women's health physiotherapist able to assess your specific condition and provide tailored exercises and advice. Manual therapy, specific exercises to strengthen the muscles supporting your pelvis, and advice on daily activities can all help.

A pregnancy support belt or pelvic support garment can provide additional stability and relieve some of the strain on the pelvic joints. These are particularly helpful during activities like walking or standing for extended periods.

What Self-Care Is Important at 16 Weeks?

At 16 weeks pregnant, important self-care includes maintaining a balanced diet rich in calcium, iron, and folic acid; staying active with gentle exercise; getting adequate sleep; managing stress; staying hydrated; and attending all prenatal appointments. Listen to your body and rest when needed, while celebrating this more comfortable phase of pregnancy.

The second trimester often brings renewed energy and a sense of wellbeing, making it an ideal time to establish healthy habits that will support you throughout the rest of your pregnancy. Taking care of yourself is one of the best things you can do for your developing baby.

Nutrition and Hydration

Your nutritional needs continue to increase as your baby grows. Focus on eating a variety of nutrient-dense foods including plenty of fruits and vegetables, whole grains, lean proteins, and dairy products. Calcium is particularly important now as your baby's bones are hardening - aim for about 1,000 mg daily from sources like milk, yogurt, cheese, and fortified foods.

Iron requirements also increase during pregnancy to support your expanded blood volume and your baby's development. Good sources include lean red meat, poultry, fish, beans, and fortified cereals. Eating iron-rich foods with vitamin C-containing foods can enhance absorption.

Staying well-hydrated is essential for maintaining amniotic fluid levels, supporting your increased blood volume, and preventing constipation. Aim for at least 8-10 glasses of water daily, more if you're active or in warm weather.

Exercise and Activity

Regular physical activity during pregnancy offers numerous benefits including improved mood, better sleep, reduced pregnancy discomforts, and easier labor and recovery. Most women can continue their pre-pregnancy exercise routines with modifications, and those who weren't exercising before pregnancy can safely begin a gentle program.

Walking, swimming, prenatal yoga, and stationary cycling are excellent options during pregnancy. Aim for about 150 minutes of moderate-intensity activity per week, broken into shorter sessions if needed. Listen to your body and avoid exercises that cause pain, dizziness, or shortness of breath.

As your pregnancy progresses, you'll need to modify some activities. After the first trimester, avoid exercises that involve lying flat on your back for extended periods, as this can compress major blood vessels. Avoid contact sports and activities with a high risk of falling.

Rest and Sleep

Quality sleep becomes increasingly important and sometimes more challenging during pregnancy. Try to establish a regular sleep schedule and create a comfortable sleep environment. Sleeping on your side, particularly your left side, is recommended as pregnancy progresses to optimize blood flow to your baby.

Use pillows to support your belly and between your knees for comfort. If you wake up on your back, don't worry - simply roll onto your side and go back to sleep. Daytime naps can help if nighttime sleep is disrupted.

Emotional Wellbeing

Pregnancy brings significant emotional changes alongside physical ones. Hormonal fluctuations, anticipation of parenthood, and body changes can all affect your mood. Take time for activities you enjoy, connect with supportive friends and family, and consider joining a prenatal class or support group to meet other expectant parents.

If you're experiencing persistent sadness, anxiety, or worry that interferes with daily life, speak with your healthcare provider. Perinatal mental health conditions are common and treatable, and getting help early leads to better outcomes for both you and your baby.