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13 Weeks Pregnant (2nd Trimester): Symptoms, Baby Development (Size & Weight), and More


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Congratulations, would-be mothers! It is week 13, and you have graduated from the first trimester to the second trimester of pregnancy. The 1st trimester must have been a roller coaster ride for many moms-to-be with the high levels of pregnancy hormones showcasing a range of typical pregnancy signs.

It is normal if you haven’t experienced any of the pregnancy symptoms. However, these pregnancy symptoms can keep the to-be-mothers indulged through the second and the third trimester in a few cases.

Further through this article, know more on the baby’s developments, pregnancy symptoms, and tips to consider as we move into the first week of the second trimester.

Also Read: 12 Weeks Pregnant: Symptoms, Baby Development (Size & Weight), and More

The Baby’s Development @ Week 13 of Pregnancy or 2nd Trimerster

The baby, at week 13, measures almost 7.5-8 cm long from the head to rump (lower back). The baby’s size is comparable to a lemon or a peach. The baby is growing in full swing and weighing 25 gms. The developments of the fetus seen this week are:

The Vocal cords are Developing

The vocal cords of the baby start forming at week 13. Now that the baby’s intestines have completely moved into its new home- the fetal abdomen, the placenta is gearing up its growth process to nourish the developing fetus.  

Also Read: Leg Pain During Early Pregnancy: What does it indicate, and how can you reduce it? 

Genitals, chest muscles, and the hardening bones

The genitals are getting their gender characteristics, and the baby is moving with jerky movements at week 13. However, it is too early to feel the baby’s kicks and punches. Along with the developing muscles of the chest wall, the bones of the limbs and other bone structures begin their calcium depositing and hardening process.  

Mom-to-be @ Week 13 of Pregnancy

The 4th month of pregnancy begins with the outward and upward growth of the womb that gets more visible. The majority of the women find easing of the first-trimester pregnancy symptoms. However, some women may observe one or more following pregnancy signs this week. 

Also Read: NT NB Scan During Pregnancy: What is It, When is It Done, What Will You Find Out from the Scan?

  • Round ligament pain – Commonly occurs due to expanding uterus and associated muscles.
  • Swollen and bleeding gums or plaque formations
  • The ring of the upper stomach relaxes, causing the digestive juices to move upwards, which can lead to indigestion, heartburns, bloating, and gas.
  • Breast tenderness
  • Bowel muscles relax, instigating constipation.
  • Visible broad veins due to the excessive blood supply to the developing fetus.
  • Headaches and dizziness
  • Swelling of hands, cramping of legs
  • Oily skin with spots and Chloasma
  • Thin and shiny hair
  • Possibility of vaginal or urinary tract infection symptoms: Pain during sex, pain while urinating, reduced urinating frequency
  • Reduced fatigue
  • An increase in milky white vaginal discharge or leukorrhea sometimes produces an odor. 
  • Early pregnancy symptoms: morning sickness, weird food cravings, food aversions, hypersensitive to smell, mood swings

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Things to Consider at Week 13 of Pregnancy

Pregnant mothers need to be vigilant about covid infections while following the covid norms of social distancing, wearing masks, regular hand washes, and hygiene protocols.

  • Another aspect to be checked at week 13 is to avoid contact with people who have chickenpox or rubella. 
  • Refrain from handling cat litter as they have a single-celled parasite, Toxoplasma gondii, causing an infection called toxoplasmosis that can affect the unborn baby.
  • One of the early systems developing in the baby this trimester is the nervous system and the spinal cord. Ensure to have a minimum of 400 gms of folic acid or folate in the form of supplements or folate-loaded foods to support neural tube development. Some of the sources of folic acid include- Banana, beans, whole grains, bread, cereals, milk, and green leafy vegetables. 
  • Include calcium-rich foods like milk, milk products, salmon, broccoli, soy products, and almonds to help build maternal and fetal bone health. A good amount of calcium absorbed in the body also decreases the likelihood of preeclampsia and preterm birth.
  • While your body is making extra blood to supply the nutrients to the growing baby, your body will need iron to prevent anemia. Increase the intake of iron-filled foods such as soy products, spinach, apples, guava, dried fruits, potatoes (with the skin), and meat.
  • Complete your pregnancy diet with fiber-rich foods and plenty of water essential to fight constipation. Have small quantities of food more often to help with other stomach uneasiness. 
  • Pregnancy hormones, and the flow of gastric juices towards the mouth, can facilitate gum issues and plaque formation. Maintain healthy oral practices or meet the dentist to address these gum issues. 

Also Read: Argipreg (L- Arginine) Sachet Uses in Pregnancy, How It Should be Consumed

Is it safe to indulge in intercourse during pregnancy?

The second trimester may invariably boost your sex drive or libido because of the fared-up blood flow in the pelvic region. However, it is safe to have intercourse during pregnancy unless your consulting doctor has advised you otherwise. Pregnancy sex can encourage health benefits like accelerated postpartum recovery by pelvic floor muscle tightening, promotion of good sleep, and mood. 

Conclusion/ Take- Away

At week 13, as you move into the 4th month of pregnancy, the baby is fastly and steadily growing. The ovaries or testicles get in place, the voice boxes develop, and gear up for the first cry performance. Pregnant mothers watch out for flu, vaginal, or urine infection symptoms. If you want to get a prenatal screening done, you can still go ahead with it. Contact your doctor for pregnancy-related queries, genetic screening of the fetus, infections, or pregnancy immunization schedule. 


Overview | NHS

Pooja N Swamy (M.Sc Biomedical Sciences)
Pooja Holds Master's Degree in Biomedical Sciences from Vellore Institute of Technology. She believes in strong research and clear understanding over the subject. Always determined and focussed with a thirst to learn new things. Hardworking, flexible and grounded to align with the goals.


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