7th – Seventh week of pregnancy

During the seventh week of pregnancy the embryo measures about 13 – 17 mm and still looks like a small tadpole with a tail (which is nothing more than an extension of the coccyx), a tail that will disappear within a couple of weeks.

Due to its current size, many expectant mothers when they see it in the ultrasound compare it to a bean.

During these days, the process of ossification of the embryo’s skeleton begins. Therefore, to promote proper bone formation, it is essential that you pay particular attention to both your diet (eat more fruit, vegetables and bran) and the lifestyle you lead.

The embryo at 7 weeks

During this week, the embryo – which is measured from the highest point of the curvature of the head to the lowest point of the curvature of the tail (called Crown-rump length (CRL)) – measures approximately 13 – 17 mm 

The development of the facial and sensory organs

The cornea and retina attach to each other, forming the eyes. In this phase, the jaw, the mouth, the teeth, the tongue, the tip of the nose also begin to develop; while small veins begin to originate under the thin layer of skin. The inner ears also continue to grow.

The development of the internal organs of the embryo

This is also the week that the liver of the unborn baby begins to produce erythrocytes (red blood cells) until the bone marrow is mature enough to produce them. The appendix and pancreas begin to form, which will release the hormone insulin to aid digestion. From the yolk sac and the allantois, the umbilical cord is formed , which will replace the yolk sac itself as a source of nutrients for the embryo. Even the gonads are beginning to form: it is still too early to determine the sex of the unborn child through an ultrasound.

The kidneys are already in place: they will soon start producing urine which will form a significant amount of amniotic fluid.

Growth of arms and legs

These (small) limbs begin to flatten and form cartilage (which will then turn into bone) in preparation for the subsequent growth of hands, feet and fingers. Similarly, elbows also begin to form as the upper limbs stretch.

The development of the nervous system of the embryo

The nervous system of the unborn child continues to grow: think that about 100 new neurons are formed every minute. The prosencephalon is divided into two parts, from which the two cerebral hemispheres will subsequently originate. In the following paragraphs, we will see together what changes take place in your body during this period.

What happens to the woman’s body

Most mothers put on some weight at this stage of pregnancy (however, on the contrary, those who suffer from morning sickness may even lose weight during these weeks) and clothes start to get tighter, especially around the waist. life.

On average, weight gain during the entire pregnancy should be (indicatively) around  :

  • 5 and 18 kg for single pregnancies;
  • 11 and 25 for twin pregnancies;

(There are insufficient data to establish the recommended weight gain for women with multifetal pregnancy. 

This increase is due to various factors. The main ones are due to:

  • fetal growth,
  • the enlargement of the maternal organs,
  • the accumulation of fat and protein on your part,
  • the increase in the volume of your blood and body fluids.

The feeling of swelling is accentuated. Urination is frequent. You may have problems with constipation, and pain in the lumbar part of the back.

If you haven’t already, you can start considering buying  more suitable clothes , especially in view of future weight gain.

Other pregnancy symptoms during this week are swollen legs and breasts (the breasts get bigger as the body prepares to produce breast milk for the unborn baby).

Also, in this stage, a mucus plug is formed in the cervical canal to keep the uterus sealed and safe. This mucus plug will automatically dissolve at the time of labor and delivery.

Ultrasound at week 7

Transabdominal ultrasound will show an increase in the size of the uterus; but the child is still too small to be detected. While with transvaginal ultrasound  it is almost guaranteed that you will be able to see both the embryo and perceive its heartbeat.

In both cases, the ultrasounds do not cause any harm to the baby and, therefore, do not worry every time the doctor asks you to do one!

The ultrasound will show two black dots, partially covered by the eyelids which, later, will give life to the eyes of the unborn child. The images will continue to show a head that is disproportionate to the rest of the body due to the rapid growth of the brain.

Below we will talk about the symptoms that can occur during this week and see which of them could herald complications.

Finally, we will talk about some curiosities related to this week.

7th week of pregnancy: symptoms

During this week most women continue to experience the common symptoms of pregnancy , but it is also possible that none or only a few will appear. Having no symptoms does not mean that something is wrong or that your pregnancy is not normal. You may have them a little later than other moms-to-be, or you may be one of the few who doesn’t have a difficult first trimester.

Emotional symptoms ( depression and mood swings) and tiredness may increase over the course of this week and there’s not much you can do about it. Try to stay fit and active by eating healthily and often (every few hours), drinking plenty of water, and exercising (if you’re in a position to do so). Also give yourself permission to sleep in on the weekends and/or take a nap when you can.

During this week over 80% of women also experience some sort of nausea and more than half experience some vomiting as well. These morning discomforts usually go away by the second trimester. Although they are defined as morning, they can arise at any time of the day. To limit them and manage them better, try to eat smaller and more frequent meals; drink plenty of water in small sips throughout the day; and avoid lying down immediately after eating. The symptoms of morning sickness may be more severe in women who are pregnant with twins or triplets, and this is due to the high levels of hormones. Although in rare cases, nausea could turn into its own disease called hyperemesis gravidarum. This disturbance can lead to nausea for the entire duration of pregnancy, and must be treated with rehydration drips (to be done in the hospital); in the most serious cases, hospitalization may be necessary in order to prevent possible damage to the mother and child due to poor nutrition and hydration.

Progesterone , the pregnancy hormone, slows down some body functions, including digestion, and this promotes excess gas buildup in the gastrointestinal tract (meterorism) and constipation . Limiting carbonated drinks, avoiding greasy or fried foods, eating smaller meals (but eat more often), drinking lots of water, eating slowly, and chewing your food thoroughly can help prevent excess gas.

In some cases, however, hormonal changes can also trigger diarrhea . If so, the most important thing to do is stay hydrated. So drink lots of water and juices, and eat soups and soups. If diarrhea doesn’t go away on its own within two days, call your doctor.

Other frequent symptoms during the 7th week of pregnancy are pain in the lower abdomen , which can be caused by the accumulation of air, by the lowering of the uterus, by constipation.

Excess saliva is a real symptom of pregnancy even if not all women notice it. It serves to protect the mouth and throat from stomach acids. Drinking lots of water, using mouthwash, brushing your teeth often, and chewing gum might help tame the drool.

Most often this period is accompanied by frequent urination , caused by the expansion and lowering of the uterus and the increase in the hormone HCG, which causes increased blood circulation in the pelvic area. In the second trimester, the uterus should rise again giving you some relief.

Those seen above are the “classic” and most frequent symptoms, but they can also be accompanied by others:

  • mild vaginal bleeding or spotting ;
  • trouble sleeping (due to restless legs syndrome or pregnancy hormones);
  • whitish cervical mucus ;
  • excessive thirst and dry mouth (may indicate gestational diabetes )
  • hot flashes (due to increased blood circulation);
  • shortness of breath ;
  • chest pains ;
  • pain in legs and joints .

Seventh week of pregnancy risks: when to call the doctor

It is advisable to call the doctor immediately, but without alarm, if the following circumstances occur:

  • rapid weight loss;
  • sharp abdominal pain on one or both sides;
  • heavy bleeding;
  • yellowish or brown vaginal discharge;
  • continuous fever for 24-36 hours;
  • vomiting more than three times a day;
  • formation of blood clots;
  • severe lower back pain.

Curiosity and advice about this period

  • In this period the fetus, as you will have also been able to see from the ultrasound scans, is still small and therefore you still cannot “feel” it in the belly.
  • It is not entirely clear why a woman suffers from nausea during pregnancy: one of the most logical hypotheses is that the disorder appears to prevent the expectant mother from eating foods that could be bad for her and the baby. In fact, when you suffer from nausea you tend to eat healthier, lighter and fresher foods. 
  • If you suffer from heartburn , avoid lying down immediately after meals and during meals. drink little (drink abundantly and frequently, but away from meals).
  • Against abdominal swelling, try to avoid taking foods containing yeast (such as bread, pizza, etc.). Break up your meals and chew slowly. To this end, herbal teas based on fennel and anise could help you.
  • Against constipation, try to eat lots of vegetables and lots of foods rich in fiber. Drink lots and try to take long walks. Eliminate milk and dairy products, this could help you regain intestinal regularity. Some mothers benefit from taking a spoonful of extra virgin olive oil before meals (to “lubricate” the intestine).
  • Before pregnancy, only about 2% of total blood flow was to the uterus; towards the end of the first trimester of pregnancy, however, it will reach 25%.
  • Starting from these first weeks, you may observe an increase in heart rate of about 8-16 beats/min, and a drop in blood pressure (about 10-20 mm/Hg). Don’t worry, it’s a physiological and normal phenomenon. If you are not already monitoring your blood pressure you may want to start this good habit and do it once every 1-3 weeks (depending on what your doctor recommends).
  • Anemia – physiological during pregnancy – is due to an increase in blood circulating in your body, which goes from about five liters to about seven litres. However, iron supplementation will not necessarily be offered to you, since it does not bring any health benefits to you or the fetus and may even have unwanted side effects.
  • The hormonal changes you are experiencing could cause skin impurities. This is due to hormonal changes.

Advice for the seventh week of pregnancy

Even in this phase of pregnancy, it is always a good idea to try to follow a healthy and balanced lifestyle.


  • absolutely stop smoking and drinking alcohol (if you haven’t already);
  • Doing hair treatments, even 3 to 4 times a week, does not appear to increase the risk of adverse effects on the fetus as they have minimal systemic absorption and the chemicals used for treatments are unlikely to reach the placenta.
  • according to a 2017 review of several articles published in Pubmed, common cosmetic treatments can be performed without risk even during pregnancy and breastfeeding. In particular, the researchers concluded that :
    • surgical treatments should be avoided until the second trimester of pregnancy,
    • judicious use of lidocaine with epinephrine and topical prilocaine / lidocaine preparations is safe
    • minor treatments such as shaving biopsy or lesion removal are considered safe due to their minimally invasive nature
    • glycolic acid and lactic acid peels are probably safe to use due to limited dermal penetration, but solutions containing salicylic acid should be used with caution due to higher absorption rates.
    • trichloroacetic acid (used for superficial or medium peels) has been associated with low infant birth weight. These peels should therefore be used with caution, especially due to the risk of dermal penetration.
    • the use of botulinum toxin A is considered safe
    • there is little evidence to support the safety of fillers during pregnancy.
    • sclerotherapy should not be hastily considered in pregnant patients as varicose veins may improve after delivery. Laser and light therapy appear to be safe for treating genital warts and ureteral stones in pregnant patients. However, the lack of safety evidence in a cosmetic context prevents a concrete recommendation on laser and light therapy during pregnancy.
    • Since excess body hair growth may resolve after delivery, temporary hair removal treatments are recommended during pregnancy.
  • avoid products against mosquitoes and insects: if absolutely necessary, use products based on N,N-Diethyl-meta-toluamide (DEET or diethyltoluamide) or PMD (para-menthane-3,8-diol; C10H20O2), although specific studies on its use in pregnancy are scarce on the latter; 
  • follow a healthy diet, as varied as possible and containing all the nutrients, based on vegetables and fruit which are foods rich in vitamins and minerals necessary for the growth of the child;
  • for your own good and that of your fetus, do some physical movement, which, even if done in a moderate way, will help you not gain excessive weight during the first trimester; 
  • consult your doctor if you need to take anti-anxiety drugs (such as Xanax);
  • Check with your doctor about blood tests and complete blood counts. With these tests -it will be possible to check your liver and kidney function -your blood group will be identified -it will be possible to see whether or not you have had rubella, hepatitis C, TB and, above all, if you are immune to Toxoplasmosis
  • consult the dentist in order to maintain correct oral hygiene: poor dental or gingival health conditions could affect the development of the child, or increase the risk of premature birth;
  • nausea in pregnancy can be effectively combated with a combination of vitamin B-6 and doxylamine.

Ultrasound at 7 weeks of pregnancy

If not already done the week before, the first ultrasound is performed during the seventh week of pregnancy, a non-invasive diagnostic method in which the embryo can be seen. The latest generation ultrasounds allow you to hear even the heartbeat.

Below we report the video of a three-dimensional ultrasound at 7 weeks (The three-dimensional ultrasound uses the same technique as the two-dimensional ultrasound but, while the two-dimensional ultrasound provides images in 2 dimensions, the three-dimensional one makes a computerized 3D reconstruction of the ultrasound signal of the structures being examined).

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.

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