Fourth Month of Pregnancy: Entering the Second Trimester

Highlights

• The start of the second trimester, often described as the most comfortable stage.
• Morning sickness usually subsides, appetite improves, and energy returns.
• Uterus grows beyond the pelvic area; first fetal movements may be felt.
• Placenta fully formed, ensuring oxygen, nutrition, and protection for the fetus.
• Common issues: constipation, varicose veins, mild abdominal pain, or nosebleeds.
• Fetal development includes swallowing reflex, nail and hair growth, and organ maturation.
• Ultrasound can determine the baby’s sex; genetic screening tests may be performed.
• Balanced nutrition, moderate exercise, and preventive care are essential.

In This Article

• Maternal body changes during the fourth month
• Weeks included (14–17 weeks)
• Fetal growth and developmental milestones
• Nutrition and dietary recommendations
• Physical activity and lifestyle adjustments
• Sexual activity and precautions
• Medical check-ups and screening tests
• Practical tools and assistance for expecting parents

Overview

The fourth month marks the beginning of the second trimester, often considered the calmest stage of pregnancy. Hormonal levels stabilize, morning sickness typically fades, and overall well-being improves. Embryogenesis is complete — major organs are formed and continue developing actively. The fetus usually positions itself head down within the amniotic sac, while the placenta takes full responsibility for sustaining growth.

Maternal Changes

• Uterus and ligaments: Continued growth of the uterus may cause mild, short-lived pain in the groin due to ligament stretching.
• Circulation: Increased blood volume sometimes results in nosebleeds, easy bruising, or excessive sweating. Proper hydration and humid air help alleviate these effects.
• Digestive system: Hormonal influence slows intestinal activity, leading to constipation, which may trigger hemorrhoids. Varicose veins can appear on the legs, breasts, or external genitalia.
• Fetal movements: By the end of the month, light movements may be felt, particularly by individuals with a lean build or those in subsequent pregnancies.
• Appearance: The waistline begins to round, and the pregnancy bump becomes visible by week 17. Skin on the abdomen may itch or feel dry, increasing the risk of stretch marks.

Weeks Included

• Week 14: Fetus about 80–113 mm, ~25 g (size of an apple).
• Week 17: Fetus about 11–12 cm, ~100 g (size of a pear).

Nutrition

• Daily caloric intake should increase by ~300 kcal to support rapid cell growth.
• Priority should be given to protein-rich foods (meat, fish, dairy, legumes) rather than excess carbohydrates.
• Include fresh vegetables, fruits, grains, and healthy fats (nuts, plant oils).
• Vitamin supplementation may be necessary; prenatal vitamins are usually recommended.
• Iron and Vitamin C help prevent anemia and strengthen blood vessels.
• Small, frequent meals aid digestion and help manage constipation.

Fetal Development

• Placenta function: Fully active, providing nutrients, oxygen, and immune protection while filtering waste.
• Reflexes: Swallowing and sucking reflexes develop; the fetus may suck its thumb.
• Physical features: Hair, eyelashes, eyebrows, and nails begin to grow.
• Organ activity: Kidneys and bladder function, expelling urine into the amniotic fluid, which renews several times a day.
• Sensory development: Eyes start opening, and sensitivity to light emerges by the end of the month.
• Measurements: By the fourth month, the fetus is about 20 cm long and weighs ~200 g.
• Screenings: Ultrasound can usually determine the sex. Blood tests (AFP, hCG, estriol) may indicate chromosomal abnormalities; if results are abnormal, procedures like amniocentesis may be recommended.

Sexual Activity

Sexual relations during the second trimester are usually considered safe unless contraindicated by:

• Placenta previa (low placenta position)
• Threatened miscarriage
• Premature rupture of membranes
• Multiple pregnancy with complications

Some report heightened desire, while others prefer abstinence. Communication and comfort between partners are essential.

Lifestyle and Recommendations

• Oral health: The fourth month is an appropriate time for dental care, as mild anesthetics can be used safely.
• Physical activity: Walking, swimming, yoga, or other gentle exercises are beneficial. High-risk sports (cycling, skating, horseback riding) should be avoided.
• Clothing: Loose, breathable fabrics and supportive undergarments are recommended. Compression stockings may help with varicose veins.
• Rest: Sleeping on the left side improves circulation to the placenta. A maternity pillow can provide comfort.
• Self-care: Moisturizing creams help prevent stretch marks. Hair coloring and nail polish are not strictly prohibited, but gentle, low-chemical alternatives are advisable.
• Constipation prevention: Adequate hydration (1.5+ liters daily), fiber-rich foods, and moderate activity are recommended.

Tools and Assistance

• Pregnancy trackers to calculate weeks and monitor progress.
• Prenatal vitamins and supplements to prevent deficiencies.
• Maternity pillows to improve sleep and later serve as nursing pillows.
• Compression wear to reduce swelling and varicose veins.
• Support groups and communities (online/offline) to share experiences and gain advice.
• Healthcare professionals: Regular check-ups with obstetricians and referrals to specialists when needed.

Summary:
The fourth month of pregnancy signifies stability, improved well-being, and visible signs of fetal growth. With morning sickness fading, appetite returning, and energy increasing, this stage allows better preparation for the months ahead. Balanced nutrition, proper rest, regular medical check-ups, and supportive lifestyle choices contribute to a healthy progression into the second trimester.