13 week of pregnancy
Congratulations, you’ve made it through a third of your most difficult journey to motherhood. The first trimester has ended and the second trimester begins, with a significant drop in the risk of miscarriage1, and with your baby having completed the formation of the main organs and body parts.
The development of the fetus in the 13th week
The development of internal organs
The baby’s intestine continues to position itself in its new location inside the abdomen;
The major organs begin to function, with the pancreas producing insulin, the liver secreting bile, and the kidneys producing urine to transport waste products out. During this stage of pregnancy, urine is released into the amniotic fluid that surrounds the baby.
The testicles or ovaries – depending on the sex of the fetus – have already finished growing. 2 A female fetus will now have about two million ova in her ovaries, and this number will continue to increase before falling back to one million at the time of birth. 3
The vocal cords begin to form.
The development of bones and muscles
Around this time, bone begins to grow in the tiny arms and legs, while sucking muscles begin to develop inside the cheeks.
The baby has already started to practice his reflexes which he will then need while breastfeeding, swallowing the amniotic fluid.
The development of the limbs
This is the week during which the baby begins to develop – on his fingertips – his unique fingerprints.
By this week, since the fetus has started moving its tiny arms and legs, the baby is now able to put its thumb in its mouth.
The external appearance of the fetus
Your baby looks more and more like a tiny human being, with his head and body gradually proportioning.
Now his head represents only one third of his total body.
The size of the child
Your little miracle is now 7.4 cm long. – about the size of a peach – and weighs about 25 grams.
The changes in your body during 13th week
From the thirteenth week, the morning sickness that has plagued you for the last 3 months begins to disappear, along with many of the other exhausting symptoms.
It is normal for you to feel a little awkward at this stage, due to the relaxin hormone which relaxes your joints, muscles and ligaments.
You may also notice your rib cage expanding slightly to accommodate your growing uterus, while your belly button may have already begun to protrude.
You may still need to go to the toilet more frequently than usual, but the frequency will soon decrease as the uterus moves out of the pelvis and bladder. The uterus is gradually moving upward, causing a small bump to form in your belly.
However, it is still too early for anyone – besides you – to notice it, especially if you are pregnant for the first time.
Subsequent or twin pregnancies may cause her to be seen sooner.
The ultrasound at the thirteenth week
The skin of the fetus is still transparent, and an ultrasound scan allows you to see its developing blood vessels and internal organs.
Although the sex organs have nearly completed their development, it is often too difficult to determine the baby’s sex via an ultrasound at 13 weeks.
A Doppler ultrasound, your baby’s heartbeat may seem alarming to you, because it is twice as fast as yours. However, his heartbeat will gradually decrease, until it normalizes before birth. An ultrasound will show the baby moving in jerks, kicking and flexing her little arms. However, it is still too early for you to perceive these movements of him.
Symptoms at 13 weeks
On the bright side this week, early pregnancy symptoms such as nausea, vomiting, fatigue, mood swings, food cravings and heightened sense of smell are finally starting to disappear, and you’re entering the second trimester, which is often considered the least symptomatic of the three trimesters.
Another good thing that happens during this week or so is that your energy levels start to rise again and you will feel less sleepy day after day.
However, you don’t need to worry if you still feel weak, tired and nauseous, as every pregnancy is unique with its own symptoms and ailments.
These are the symptoms that are common in the thirteenth week:
- an occasional sharp abdominal pain due to the uterus putting more pressure on the abdomen;
- a pain in the round ligament of the uterus (in fact, the ligaments begin to pull and stretch to support the rapid growth of the uterus itself);
- pain in the back, joints, hips and pelvis;
- visible veins, especially around the breasts and abdomen, due to increased blood flow;
- indigestion and heartburn due to the increased pressure on the gastrointestinal tract, and due to the levels of pregnancy hormones which slow down the digestion process even more;
- bloating, bloating, flatulence;
- constipation due to pregnancy hormones;
- shortness of breath;
- insomnia;
- appearance of stretch marks on the abdomen, sides and buttocks;
- larger breasts (as the pregnancy progresses, the soreness begins to gradually disappear);
- mood swings that may be less frequent than in the first few weeks;
- food cravings or an increased appetite;
- occasional dizziness and fainting;
Signs to pay particular attention to4
- Unexplained vaginal bleeding associated with other symptoms such as abdominal cramps, nausea, lower back pain, dizziness: it could be an indication of serious complications or even a miscarriage;
- nausea and vomiting lasting more than 12 hours, so severe that you cannot keep any fluids down, as they increase the risk of dehydration;
- clear or straw-colored vaginal discharge, which could indicate amniotic fluid leakage;
- a pain and/or burning sensation when urinating which could indicate the existence of a kidney or urinary tract infection;
- severe pain in the upper abdomen, along with blurry vision, nausea and headaches , which could indicate high blood pressure or pre-eclampsia;
- bleeding, or bright red specks of blood;
- severe difficulty in breathing, associated with tiredness, palpitations and chest pain, which could indicate the presence of anemia;
- severe fatigue, or feeling always exhausted;
- a sudden increase in vaginal discharge;
- flu-like symptoms such as runny nose, sore throat, cough, fever and chills.
Advice for a peaceful pregnancy and a healthy baby4
- use part of your regained energy to do regular physical activity such as, for example, taking a short walk or swimming: your doctor will be able to give you advice for your specific case;
- avoid wearing clothes that are too tight as they could put pressure on your tummy: if you are short on clothes, consider buying some suitable maternity clothing;
- consider enrolling in prenatal yoga classes and education classes for new mothers;
- avoid making sudden movements, such as standing up or turning around too quickly, as they could cause dizziness and pain in the ligaments;
- Ask your doctor for advice about having sex if you’ve had miscarriages, preterm deliveries, or a condition called placenta previa (when the placenta inserts into the lower part of the uterus covering the cervix.
- eat a healthy, well-balanced diet to prevent sudden weight gain (now that you’re starting to get hungry again, you need about 300 extra calories);
- in your daily diet include foods that contain a lot of iron, proteins, and also vegetables rich in calcium, which are the most essential nutrients for correct fetal growth;
- continue to take the “prenatal” vitamins;
- sleep on your side , because sleeping on your stomach is not recommended from now on;
- consult your doctor if you are considering using anti-stretch mark lotions or creams;
- perform all necessary prenatal checkups.
Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.
She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.