You have made it through the most challenging one-third of your journey to motherhood. The first trimester is almost over with the risk of miscarriage dropping significantly and your baby having grown all the principle organs and body parts. Check out the fetal growth this week as well as the warning signs that call for medical attention.
Fetal development in week 13
Internal organ development
The intestines continue settling in their new and permanent place in your baby’s abdomen with the construction of the vocal cord beginning at the same time . The major organs start working around the same time with the pancreas producing insulin, the liver secreting bile and the kidneys forming urine for carrying away any waste materials. At this stage, the urine is passed in the amniotic fluid surrounding the baby .
The testes or ovaries are already done growing depending on the sex of your baby . A female fetus will now have around two million eggs in the ovaries, which will go down to one million at the time of birth .
Bone and muscle development
Bony tissues start to grow in the tiny arms and legs around this time , while sucking muscles begin developing in the cheeks. Your baby has already started practicing the reflexes he will later need while nursing .
This is the week when your baby starts developing unique fingerprints at his fingertips . Since he has already started moving those tiny arms and legs, your baby may even be able to put his thumb into the tiny mouth by this week .
Your baby is looking more and more like a tiny human with the head and body gradually coming into proportions. The head constitutes only one-third of the total body now . However, there is still no fat , which makes him look quite thin and pinkish. This is also the week when the external genital organs start to develop .
How big is the baby at 13th week of pregnancy
Your tiny miracle is now 2.9 inches (7.4 cm) long, about the size of peach, weighing around 0.81 oz (22.9 gm) .
Your body changes in pregnancy week 13
The morning sickness that has kept you down for the last 3-4 months starts to retreat by the 13th week along with many of the other exhausting symptoms. You may still need to use the bathroom oftener than usual, but the frequency will soon start going down due to the uterus moving away from the pelvic bones and bladder .
You may also notice your ribcage expanding a little to accommodate the growing uterus while your bellybutton may already stat to stick out as well . It is normal to get a bit clumsy at this stage due to the relaxin hormone released by your body that relaxes the joints, muscles and ligaments .
How does 13 weeks pregnant look like?
The uterus is gradually moving upwards, causing a small bump to develop in your belly . But, it is still too early for anyone to notice it but yourself, especially if it is your first pregnancy. Subsequent pregnancies or carrying twins may make you show earlier.
13 weeks pregnancy ultrasound
The still see-through skin  makes it possible to view the growing veins, blood vessels and internal organs on an ultrasound image. Although the sex organs are almost done developing, it is often too difficult to determine the gender of the baby with ultrasound during the 13th week .
Your baby’s heartbeat may sound quite alarming on a Doppler device as it is currently twice as fast as your own. But it will gradually slow down to normal before birth . An ultrasound will also show your baby making jerky movements, kicking his legs and flexing those tiny arms, but it is still too early for you to feel these movements .
Pregnancy week 13 signs and symptoms
On the positive side, your early pregnancy symptoms of nausea, vomiting, fatigue, mood swings, food aversions and increased sense of smell are finally starting to go away as you are entering your second trimester, often claimed to be the least symptomatic of the three . Another great thing about this week – your energy levels start to go back up  as you feel less and less drowsy with each passing day. However, there is nothing to worry about if you continue to feel weak, tired and nauseated as every pregnancy is unique with its own symptoms and complaints. Here are the common signs of the 13th week:
- Occasional sharp abdominal pain (due to the uterus putting more pressure on your abdomen) 
- Round ligament pain (as the ligaments begin to pull and stretch to support the rapidly growing uterus) 
- Back pain, hip, joint and pelvic pain
- Visible veins, especially around your breasts and abdomen (due to the increased blood flow) 
- Indigestion and heartburn (because the increased pressure on the gastrointestinal tract and the higher pregnancy hormone levels further slowing down the digestive process)
- Bloating, gas, flatulence and burping 
- Feeling out of breath 
- Difficulty sleeping (insomnia)
- Appearance of stretch marks on the abdomen, hips and buttocks 
- Enlarging breasts (the symptom of breast tenderness starts to go away gradually as you advance in your pregnancy)
- Mood swings (might be less frequent than in the earlier weeks)
- Pregnancy cravings or increased appetite 
- Occasional spells of dizziness and fainting 
When to call the doctor?
- Unexplained vaginal bleeding along with symptoms like abdominal cramps, nausea, lower back pain and dizziness (might indicate serious complications or even a miscarriage) 
- Severe nausea and vomiting that prevents you from keeping any fluid down for over 12 hours (increases risks of dehydration) 
- Clear or straw colored vaginal discharge (might indicate leaking amniotic fluid)
- Pain and/or a burning sensation while urinating (might indicate a kidney infection or UTI)
- Considerable upper abdominal pain along with vision changes, nausea and headache (might indicate high blood pressure or preeclampsia) 
- Bright red bleeding or spotting
- Experiencing severe breathing difficulty accompanied by tiredness, palpitations and chest pain (might indicate iron deficiency or anemia) 
- Sever fatigue or feeling exhausted all the time
- Sudden increase in vaginal discharge
- Experiencing flu-like symptoms including runny nose, sore throat, cough, fever and chills 
Tips for a healthy pregnancy and baby
- Utilizing the extra energy in your regular exercise routine and going for a short walk or a swim
- Although it is probably too early for maternity clothing, it is advisable to avoid tight clothes that might put pressure on your belly
- Considering joining prenatal yoga and childbirth education classes 
- Avoiding sudden movements such as standing up or turning too quickly as it might trigger lightheadedness  as well as ligament pains
- Avoiding intercourse if you have a history of miscarriage, preterm labor or a low lying placenta (placenta previa) 
- Following a healthy well-balanced diet to prevent sudden rapid weight gain now that you are starting to feel hungry again (you only need around 300 extra calories)
- Including plenty of iron, protein, and calcium-rich fruits and vegetables in your daily diet as these are the most essential nutrients for proper fetal growth
- Continuing to take your prenatal vitamin
- Sleeping on your side (preferably the left side) as lying on your stomach is not recommended from this period onward
- Making sure to consult your doctor if you are considering using any anti-stretch mark lotion or cream 
- Attending all your prenatal appointments and check-ups
- www.fitpregnancy.com/13-weeks-pregnant [/ref]