Pregnancy Week 13 – Weekly Development

You would think that week 12, which is, of course, the end of the third month would mark the end of your first trimester. However, pregnancy weeks are counted quite differently and week 13 officially marks the end of your first trimester according to the American College of Obstetricians and Gynecologists.

At 13 weeks, miscarriage rates would have reduced significantly since you’re at the end of your first trimester. This week sees a lot of development in both your body and your baby.

Your hormone levels are beginning to balance well and the placenta that started to develop some weeks ago is fully in charge of catering to your baby’s needs.

Your belly would see some expansion this week and it would begin to come up and out of your pelvis. If you’re still rocking your regular clothes, you may not feel comfortable any more. You would need the stretch and extra room that clothes with maternity panels can provide you.

Your symptoms are going to take a major step back and you can finally keep your eyes open more and enjoy your food with a healthy appetite.

Now may be a good time to let people know that you’re pregnant; your coworkers, friends, and family (if you haven’t told them). Your stomach would bulge really fast in the next couple of weeks and the cat would be out of the bag. 

Your baby is now about the size of a lemon.

Your Baby’s Development

Recall that your baby’s head was almost the size of its entire body. Well, that has changed. The head is about half the size of its entire body and has been that way for a while now.

And this week, there would even be some more reduction in size—your baby’s head would reduce to about one-third of its body size. 

Your baby is measuring up to 3¾ inches (9.5 centimeters) and is about the size of a peach. Transparent and delicate skin is starting to see some growth.

Soft, fine hair known as lanugo is beginning to cover the skin and would come in pretty useful later on to keep vernix, a naturally occurring biofilm, on your baby’s skin. This biofilm prevents amniotic fluid from coming in contact with the skin.

Fingerprints formation is complete and present on the tips of all 10 fingers. The placenta continues to supply your baby with oxygen and nutrients as well as get rid of waste. Although the placenta is fully functional, it doesn’t mature completely until about 5 to 7 weeks from now.

Limb development has progressed well enough for your baby to be able to move their arms now and suck on their thumb. They may be able to make a fist too. In the mouth, vocal cords are still developing and salivary glands are working now as well.

Using an external Doppler, you can hear your baby’s heartbeat, and the lungs are maturing, allowing inhalation and exhalation of amniotic fluid. The spleen is producing red blood cells already and the intestines are present in the abdomen already.

Testes or ovaries are well developed now and sex organs are beginning to show although they are still too small to be detected by an ultrasound scan.

Your Body & Symptoms

The end of your first trimester heralds a significant reduction in your nausea and exhaustion. You would most likely experience an uprise in your energy levels and the next phase of pregnancy that you’re getting into is considered the easiest in comparison to others.

Right about now, your uterus is constantly expanding and it is gradually coming up and out of your pelvis.

This implies that you would actually start to bulge—the days of having a flat tummy are almost behind you. Your pregnant belly would be apparent to all and sundry and you may start to enjoy the preferential treatment that you deserve.

Week 13 may also bring about weight gain, so you would need to pay special attention to your diet in order to not gain excessively.

Your doctor would typically recommend that the best way to gain weight is slowly and steadily all through the period of your pregnancy.

The frequent urge to pee that you’ve been having these past few weeks would stop since your womb is shifting up and away from your bladder.

Instead, more blood pumping in your pelvic region would imply a higher sex drive. Quite a nice replacement for frequent urination.

In addition to these, here are some other symptoms that you would likely experience:

1.   Cravings

Don’t think it weird if you find yourself suddenly craving different foods at random. These cravings are a result of hormonal changes and they typically affect your senses of smell and taste.

 You may also find yourself craving sugary stuff and this may be a result of fluctuations in your blood sugar.

You would need to watch your sugar intake, and instead of going for junk, opt for sweet fruits, vegetables, and healthy snacks.

Ensure that your diet has sufficient protein to help stabilize your blood sugars all day. It is advisable to consume at least 70 grams of protein every day.

2.   Increased Sex Drive

You might feel your libido going through the roof, this is as a result of the extra blood circulating in your pelvic region. Your sex drive might also be accompanied by an increase in energy so that you don’t feel extremely fatigued afterward.

Sex during pregnancy is considered safe, provided there are no cases that require special attention such as vaginal bleeding or placenta previa. You may experience mild cramping post-orgasm, but it is no cause for alarm—your uterus is only undergoing some mild contractions.

Around this time, you may experience some spotting after sex. This is pretty normal because your cervix has become a lot more sensitive. However, if you experience some heavy bleeding, similar to period flow, you need to see your doctor immediately.

3.   Boost In Energy

You would start to feel a lot more energetic compared to the days when getting out of bed felt like lifting a heavy weight.

The new trimester marks a period where you get fewer symptoms and you start to feel more like your former self again. If you gave up on exercise because you were feeling too weak and pretty sick, now is the time to pick it up again.

Fitness routines have lots of advantages and are known to make the labor process a lot easier. Also, now is the time to pick up that to-do list that has been lying around for weeks and get to completing those tasks!

4.   Visible Veins

You may notice blue streaks under your skin, they are simply more veins popping up. Your body is circulating an increased volume of blood and requires your veins to do more work per time.

 Lightheadedness from time to time is nothing amiss, blame it on fluxes in your blood sugar level and increased circulation.

Measures To Begin To Observe

1.   Watch Your Weight/ Eat Healthily

There is a tendency for you to add weight significantly during this week, especially if you do not watch your diet. Eliminate junks and stick to healthy food that provides all the essential nutrients.

If you feel constipated from time to time, reduce your food intake per time. You could consume small proportions of food throughout the day, giving your digestive system less work to do.

This would make your digestion process more efficient and you would experience minimal levels of bloating and gas. 

2.   Don’t Quit Taking Your Prenatals

Folic acid or folate is very essential for the development of your baby’s spinal cord and nervous system which are among the first organ systems to begin to develop.

It can be found in food such as beans, green leafy vegetables, broccoli, whole grains, milk, and bananas. It is also important for neural tube development and is, therefore, one of the most vital components of your prenatal.

In addition to eating foods rich in folic acid, supplements containing folic acid are advised as well and you should typically start to take them when you start trying to get pregnant.

The recommended amount is about 400 micrograms before you’re pregnant and 600 micrograms upon confirmation of pregnancy.

3.   Maintain Good Hygiene

Good hygiene is important whether or not you are pregnant. However, while you are pregnant, you are significantly more susceptible to minor ailments such as colds and flu. This is because your immune system becomes naturally repressed to accommodate the foreign body that is your fetus.

Therefore, in order to stay healthy, you would need to maintain very high hygiene standards. Wash your hands more often and ensure that your food isn’t contaminated in any way. Also, if you feel like you have picked up a bug, see your doctor immediately.


The beginning of next week would mark the start of your second trimester and you would start to feel a whole lot better.

However, this doesn’t imply that you should cut yourself some slack with respect to all the measures that you have been taking in previous weeks. If anything, it should be more like a routine and one that you shouldn’t skimp on at all.

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