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Week 13 of Pregnancy: All You Need to Know

Baby’s Development|Body and Life Changes|Your Doctor Visits |Health and Safety
Week 13 of Pregnancy: All You Need to Know

Baby’s Development

How is my baby growing?

Week 13 of pregnancy baby development marks the end of the first trimester. The baby should be around three inches long and weighs about 25 grams. Their head will also be significantly bigger, becoming more balanced with the rest of the body. Although you will not feel movement just yet, your baby can now move their hands and thumbsuck. This is because the tissue around their arms and legs are fortifying into bones. The baby’s intestines will return to the abdomen after forming in the umbilical cord. Moreover, they eyes are now formed but will remain closed until week 28. The baby’s ears will start to protrude, while vocal cords and teeth are developing.

Apart from these, week 13 of pregnancy baby development is characterized by the formation of sex organs. If you are pregnant with a baby boy, his penis will likely form where a bump used to be. However, an ultrasound might not be able to detect this just yet.

Body and Life Changes

How is my body changing?

During week 13 of pregnancy baby development, your bump will start to show. This is because your placenta is growing rapidly, providing oxygen to your baby. Veins under the bump are more visible as your blood flow increases. Moreover, your breasts will also start to produce colostrum, a precursor to breast milk. As a result, you might leak sticky fluid from time to time. Expect an increase in energy level and mobility, too. Symptoms like headaches and morning sickness are likely to be not as prevalent.

What should I be concerned about?

Most pregnant women are found to be most comfortable during this stage. Some even refer to it as pregnancy “glow.” However, you need to watch out for the following at week 13 of pregnancy baby development:

  • Weight gain: Your uterus continues to expand up and out of your pelvis. This results in an increase in weight gain. While normal, it should coincide with your pre-pregnancy body mass index (BMI). Hormonal changes can trigger spikes in blood sugar levels. This explains your sudden cravings for unhealthy food. Opt for healthy snacks instead. When not careful, rapid weight gain can lead to pregnancy complications like gestational diabetes and preeclampsia.
  • Round ligament pain: You might experience sharp abdominal pains due to your growing belly. This occurs when you change positions quickly.
  • Spotting and vaginal discharge: Some women might experience an increase in sex drive. In addition, post-coital spotting is normal since your cervix is more sensitive than usual. Call your doctor if it progresses into heavy flow. The same goes with vaginal discharge. White in color and usually odorless, leukorrhea is your body’s way of fighting off bacteria. If it emits a foul odor and changes in color, seek medical help. It could be a sign of preterm labor.
  • Visible veins: Blue streaks across your abdomen are more prominent.This is because your blood flow levels increase.
  • Heartburn and indigestion: The valve between the stomach and esophagus are more relaxed, causing heartburn. Moreover, muscle contractions in the stomach are slower. Your expanding uterus presses down in the stomach, making it more difficult to digest food. Eat slowly and drink water after every meal. Avoid eating spicy and greasy food.

Your Doctor Visits

What should I tell my doctor?

Contact your doctor if you experience symptoms of miscarriage or an ectopic pregnancy at week 13 of pregnancy baby development. These include:

  • Pelvic and abdominal cramping
  • Vaginal bleeding
  • Low blood pressure
  • Painful urination
  • Frequent dizziness

Moreover, consult with your doctor first if you can have sexual intercourse. There may be complications especially if you have been pregnant before, or have had a miscarriage.

What tests should I know about?

From week 13 of pregnancy baby development, you are likely to go to appointments every four or five weeks. Opt for an ultrasound to evaluate nuchal translucency. This scan detects possible chromosomal abnormalities caused by additional fluid under the baby’s neck. Sometimes, the baby’s fetal position can affect the results of a nuchal scan. Blood tests are taken for a more accurate diagnosis.

Sequential or integrated screening are helpful to predetermine defects and abnormalities. It measures placental hormones and proteins that can tell if the baby has Down syndrome or spina bifida. These proteins include Pregnancy-associated plasma protein screening (PAPP-A) and Human chorionic gonadotropin (hCG).

There are also blood tests on genetic screening which looks into the baby’s DNA. To further confirm test results, some women undergo amniocentesis and chorionic villus sampling (CVS). The former takes a sample of your amniotic fluid while the latter removes part of your placenta tissue for lab evaluation.

Taking all screening tests is not necessary. It is important to check in with your doctor which option is ideal during week 13 of pregnancy baby development.

Health and Safety

What should I know about being healthy and safe while pregnant?

As you enter week 13 of pregnancy baby development, you may have other concerns including the following:

  • Exercise: Being sedentary can increase the risks of complications. Exercising does not have to be complicated. Walking, yoga, or swimming are great options. However, find other alternatives to abdominal exercises due to your growing belly. It might also be time to tone up your pelvic floor muscles. This will be helpful when you actually give birth.
  • Caffeine: High intake of caffeine may increase risks of miscarriage, preterm delivery, and low birth weight. Opt for herbal teas instead. Chamomile, ginger, and mint contain antioxidants that boost the immune system. Herbal laxatives and “cleansing” teas, on the other hand, should be avoided.
  • Cravings: Pregnancy cravings occur usually in the first trimester to the early second trimester. In Philippine context, this is referred to as paglilihi. This phenomenon is still associated with superstitious beliefs that some Filipinas today still follow. Supposedly, what you frequently crave can influence your baby’s appearance and personality. In an interview, nutritionist Jo-Ann Salamat clarifies that it is genetics, not food, that determines what the traits inherited from parents.
  • Diet: You are likely to gain weight due to your growing belly. It is important to watch your portions and instead focus on eating healthy. Eat iron-rich food like spinach, dried fruits, beans, and lentils. These will help maintain a good flow of blood supply.

The end of week 13 of pregnancy baby development means you are well on your way through the second trimester. During this stage, your baby’s bones begin to form, allowing small movements. Teeth, vocal cords, eyes, and sex organs are likely to develop. Physical changes on your part are also observed. Since your uterus is growing up and out of your pelvis, you will start to show a baby bump. As a result, you will experience an increase in weight gain. While normal, be cautious in your food intake. Focus on clean and healthy eating instead of portion size. Trimester two is crucial for the baby’s development. If you experience unusual symptoms like bleeding, pelvic and abdominal pains, high temperature, and frequent nausea, call your doctor. These might be indications of miscarriage or ectopic pregnancy.

Hello Health Group does not provide medical advice, diagnosis or treatment.

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Written by Honey Buenaventura Updated Sep 28, 2021
Medically reviewed by Jobelle Ann Dela Cruz Bigalbal, M.D.