6 weeks pregnant: your pregnancy week by week


MNT Knowledge Center

During week 6 of pregnancy, your baby will be taking huge developmental strides; your baby’s vital organ systems begin forming or are continuing to grow.1-4

The heart can sometimes be seen beating on a vaginal ultrasound scan at this stage – it will currently be beating at around 160 beats per minute – almost twice as fast as your heart.

This MNT Knowledge Center feature is part of a series of articles on pregnancy. It provides a summary of each stage of pregnancy, what to expect, and insights into how your baby is developing. Take a look at the other articles in the series:

First trimester: fertilization, implantation, week 5, week 6, week 7, week 8, week 9, week 10, week 11, week 12.

Second trimester: week 13, week 14, week 15, week 16, week 17, week 18, week 19, week 20, week 21, week 22, week 23, week 24, week 25, week 26.

You will also see introductions at the end of some sections to any recent developments that have been covered by MNT‘s news stories. Also look out for links to information about related conditions.

Symptoms at 6 weeks pregnant

At this stage of your pregnancy, you may not feel very pregnant because there are little if any visible physical body changes. You may, however, begin to experience physical pregnancy symptoms such as:2,3

woman sitting on bed with morning sickness
Nausea usually starts around 6 weeks of pregnancy, but it can begin as early as 4 weeks.

  • Morning sickness, feeling of being queasy with or without weight gain or loss
  • Nausea and vomiting
  • Fatigue
  • Bloating
  • Gastrointestinal symptoms such as gas, heartburn and indigestion
  • Breast tenderness
  • Food cravings
  • Increased sense of smell
  • Urinary frequency and nighttime urination.

(Note: pregnancy increases the risk of urinary tract infections from weeks 6-24, so if your symptoms are not simply from the pregnancy and you suspect an infection, speak with your health care provider about treatment.)3

Your hormones at 6 weeks pregnant

Throughout your pregnancy, you will experience variations in certain hormones, which contribute to many of the pregnancy symptoms you may experience.

Following implantation of the fertilized egg, your body begins to secrete the hormone, human chorionic gonadotrophin (hCG) which is the hormone used to detect pregnancy. HCG is responsible for regulating estrogen and progesterone and contributes to frequent urination.5

Progesterone, which is initially produced by the corpus luteum, rises throughout your pregnancy and continues to do so until the birth of your baby.

In early pregnancy, progesterone is responsible for increasing uterine blood flow, establishing the placenta and stimulating the growth and nutrient production of the endometrium (lining of the uterus). Additionally, progesterone plays a vital role in fetal development, preventing premature labor and lactation, as well as strengthening the pelvic wall muscles to prepare your body for labor.5

In addition to progesterone, the placenta is vital in secreting vital hormones during your pregnancy such as:5

  • Human placental lactogen: this hormone is believed to handle mammary gland growth, which will be important for lactation following the birth of your baby. Additionally, it plays a role in increasing nutrient levels in your blood, which is vital to the growth and development of your baby
  • Corticotrophin-releasing hormone: this hormone is not only responsible for determining how long you will be pregnant, but it is also responsible for your baby’s growth and development. Later in pregnancy, the rise in both corticotrophin-releasing hormone and cortisol not only complete fetal organ development but also provide the mother with a surge of cortisol which has been linked with maternal attentiveness, increasing the mother-baby bond.

Another vital hormone in pregnancy is estrogen, which is responsible for fetal organ development, placental growth and function and mammary gland growth, which will be important for lactation following the birth of your baby.

Additionally, estrogen is needed for regulation of other hormones produced during pregnancy.

Because of the rise in progesterone and estrogen, you may experience some not so pleasant pregnancy symptoms such as mood swings and morning sickness.

Another hormone, relaxin, can cause physical symptoms such as pelvic pain, balance difficulties and constipation, because of its role of relaxing maternal muscles, ligaments and joints.

Baby’s development at 6 weeks pregnant

At 6 weeks pregnant there are many changes in your baby’s development. Developments that are underway include:

6 week old fetus
By the time you are 6 weeks pregnant, baby’s heart will be beating around twice the rate of yours.

  • Neural tube closure
  • Facial feature formation including the eyes, nose, jaw, cheeks and chin
  • Inner ears, limb and teeth bud formation
  • Kidneys, liver and lungs development
  • Pituitary gland formation
  • Formation of the trachea, larynx and bronchi
  • Heart begins dividing into four chambers and pumps blood
  • Formation of the diaphragm
  • Umbilical cord houses the intestines for now until they move permanently to the abdomen
  • Presence of primitive germ cells responsible for the formation of male or female genitalia.

Things to do in week 6 of pregnancy

Even though it is early on in your pregnancy, your task list is beginning to grow. This is a good time to schedule a prenatal visit at which time, your health care provider will examine you and obtain necessary tests to not only confirm your pregnancy but also evaluate your health.3

Testing that may be ordered include:

  • Pap Smear (if necessary)
  • Blood work such as blood type, Rh factor, iron levels and possibly genetic and ethnicity related genetic disease testing, German measles immunity, etc.
  • Sexually transmitted disease testing
  • Urine testing to evaluate for glucose (sugar), protein, bacteria and red and white blood cells.

Lifestyle changes at 6 weeks pregnant

You will soon find out that there are many lifestyle modifications that need to be made during pregnancy and even after delivery.

General health

During pregnancy, you will need to take care of yourself and your developing baby. Be sure not to drink alcohol or smoke during pregnancy, and avoid all other toxic substances such as drugs during this time. Be sure to discuss all medications you are taking with your health care provider to ensure that you should continue use during your pregnancy. To nourish yourself and your baby, make sure you eat a healthy diet and take a good prenatal vitamin.2


Everyone wants to look their best but using permanent hair color is not recommended during the first 12 weeks of pregnancy; instead consider using a semi-permanent dye.3


While it is safe to eat fish during pregnancy, it is recommended that you limit your intake to 8-12 oz. of fish and shellfish per week.3,6

Some examples of fish that are safe to consume during pregnancy include shrimp, canned light tuna (note: mercury varies can to can), pollock, catfish, salmon, anchovies, herring, sardines, trout, Atlantic and Pacific mackerel and cod. If you plan on eating albacore tuna and tuna steak, it is recommended to limit consuming this fish to 6 oz. per week.6

Baby’s size at 6 weeks pregnant

Your baby closely resembles a tadpole and has also begun to exhibit a C-shaped curvature.1,2

Three nails next to a hammer
At 6 weeks pregnant, your baby is the size of a nail head.

He or she currently measures approximately 10 to 13 mm.4

To put this into perspective, your baby is about the size of a BB pellet or the length of a nail head.2,3

When measured, your health care provider will measure the baby from the crown to the rump, often referred to as crown-rump length.

If you have questions regarding your pregnancy, be sure to contact your health care provider.

Call your doctor if you are experiencing symptoms of an ectopic pregnancy or miscarriage such as vaginal bleeding or passage of tissue, leaking vaginal fluid, feeling faint or dizzy, low blood pressure, rectal pressure, shoulder pain and severe pelvic pain or cramping.

Recent developments on pregnancy from MNT news

Biomarker for preeclampsia detected as early as 6 weeks into pregnancy

University of Iowa researchers have discovered a biomarker that could give expecting mothers and their doctors the first simple blood test to reliably predict that a pregnant woman may develop preeclampsia, at least as early as 6 weeks into the pregnancy.

Morning sickness: symptoms, causes and treatments

Morning sickness, also known as nausea gravidarum, nausea/vomiting of pregnancy (NVP), emesis gravidarum or pregnancy sickness is a condition that affects over 50% of all pregnant females.