Early pregnancy symptoms (conception)

Some introductory information:

  • Symptoms . While the only ways to know for sure if you’re pregnant are pregnancy tests and an ultrasound exam, there are some signs and symptoms that indicate some major change taking place in the body. Before examining them, however, it is necessary to remember the first symptoms of a pregnancy,
    • are felt very subjectively,
    • may be common to premenstrual ones,
    • they do not manifest themselves in all women equally,
    • some women feel them from the first week after conception, while others only after months.
  • Time periods. The image below visually illustrates which are the relevant dates and times also regarding the facts and symptoms that we will discuss connected to the very first stages of pregnancy. By convention, a pregnancy is considered to begin on the first day of the last menstrual period (about 2 weeks before conception). It may seem strange but it is so: it is considered the beginning of the first week even if you weren’t technically pregnant at the time. This approximate criterion – defined as the “gestational age (or age) calculation method” – depends on the fact that this first day is usually calculated a posteriori, at a time when it is not possible to detect the actual date of conception by the fertilization of the egg. But also to the fact that it is based on a date that is easy to remember.

These premises are useful to understand why symptoms may not even be felt in the first weeks of pregnancy.

Once you reach the second trimester of pregnancy many of the changes that occur in the body will begin to fade, and therefore many of the symptoms of the first trimester of pregnancy will also begin to fade.

Timeline of possible first symptoms

The first hormonal changes begin in the woman’s body after conception, therefore around the third/fourth week of pregnancy (conventional ).

These changes make the levels of beta HCG soar in the first weeks , whose function is to stimulate the production of progesterone which is the main hormone of pregnancy .

The first symptoms of pregnancy derive from this increase in progesterone: mood swings, sometimes headaches, but also changes in taste and smell. (NB. In this phase the analgesic drugs could harm the fetus).

These are subjective symptoms similar (in some women) to premenstrual symptoms. We will talk in more detail about these and other symptoms and signs of this period.

Timeline summary of early pregnancy symptoms, week by week

Uterine cramps and implant discharge

cramps. The expansion of the uterus to make room for the embryo can lead to cramps and painful sensations in the lower abdomen in the first weeks of pregnancy.

System losses.  About 10 – 14 days after conception ( 4th week of pregnancy) the blastocyst implants itself in the endometrium, the lining of the uterus. This phase of the implantation (nidation or nesting) can cause bleeding similar to menstruation, losses defined as  implantation losses . Here are some of their typical signs.

  • Color : unlike those of the cycle which are generally darker and tend to brown, the losses from implantation of the embryo in the internal walls of the uterus can be white with some red traces, or bright red, light red or rose.
  • Bleeding : implant losses are never too abundant and are usually not bright red, as the amount of hemoglobin that tends to oxidize is minimal.
  • Pain: Implantation discharge may be accompanied by small uterine cramps.
  • Duration.  Unlike premenstrual bleeding, which begins with minimal bleeding and then becomes more abundant, and which can last five days on average, these losses last a few days and are destined to disappear quickly.

Missed cycle

Once the implantation is complete, the woman’s body begins to produce human chorionic gonadotropin ( hCG ). This hormone helps maintain the pregnancy, and “tells” the ovaries to stop releasing egg cells (ova) each month.

Four weeks after conception, the woman will likely miss her next period. If the woman has an irregular cycle, a pregnancy test can confirm that she is pregnant.

Most home pregnancy tests can detect hCG as early as eight days after a missed period.

The alteration of the body temperature

A slight change in body temperature can also be a first sign of an ongoing pregnancy. A woman’s temperature can also rise by a few tenths of a degree (generally 0.3-0.5°C): even more when she does physical activity or when it’s hot.

This increase depends on the activity of hormones, in particular that of progesterone.

The tiredness

During a pregnancy you can feel tired at any time: it is quite common in the beginning.

However, be careful that (only) tiredness could also be due to other reasons such as stress, fatigue, a flu, etc.

 Increased progesterone levels can also make a woman feel  sleepy and numb.

The increase in heart rate

Palpitations and arrhythmias are quite common during pregnancy. In this first phase they depend on the mechanisms of action of the hormones, while later they are linked by the increase in blood flow due to the fetus.

The mother’s heart may start pumping faster and harder around the eighth to tenth week.

Sensitivity to smells and aversion to foods

Usually, women report an increased sensitivity of their sense of smell as their possible (early) symptom of their pregnancy.

There is little scientific evidence for this sensitivity in the first trimester . In any case, this sensitivity can have a certain importance, since it can cause nausea and vomiting, and also a strong disgust for some foods.

Nausea and vomiting

Hormonal activity can induce marked and important effects on the human organism.  The activity due to the increase in hormones can cause nausea and possibly even vomiting between the fourth and sixth week following conception and throughout the first trimester of pregnancy.

Many women in the first trimester of pregnancy suffer from mild to severe morning sickness. For some it may be more intense towards the end of the first trimester, but often the second trimester improves. For some, it is a short-lived disturbance, for others it is a continuous nuisance even after the first few months.

Although said in the morning, this nausea can occur at any time of the day and even at night. It’s not clear what exactly this is due to, but hormones certainly play a role.

The changes in the breast

Between the 4th and 8th week, the first changes can be noticed in the breast that is preparing for the moment in which the baby will be born: the breast appears more tender and more swollen due to hormonal changes; while the increase in the amount of blood that flows inside it means that the veins can be seen through the skin.

Even around the 11th week  there may be changes in the nipples and breasts:

  • hormones continue to make the breasts grow ;
  • this can take on a darker color,
  • the areola, the area around the nipple, may become enlarged;
  • the circular pigmented areas surrounding the nipple may become darker in color.

Lumbar pains

The woman may experience (lumbar) pain in the lower back from the first weeks of pregnancy. This type of back pain could sometimes also be due to other reasons: stress, fatigue or other problems not related to pregnancy.

The women most at risk of lumbar pain are those who are overweight and those who already had back problems before pregnancy. Back pain can continue beyond the second trimester.

Headaches, mood swings, cravings

Headaches affect many women during pregnancy. In the first trimester , it often affects even those who don’t usually suffer from this kind of pain. It usually goes away on its own after the second trimester . Its cause is related to hormonal changes, especially those related to estrogen .

During pregnancy, estrogen and progesterone levels rise in women . These increases can also affect your mood by making you more emotional or more reactive than usual. Mood swings are common in pregnancy and can also lead to depression, irritability, anxiety and euphoria.

In this context, we can also include the infamous pregnancy cravings , those sudden, irresistible, urgent desires to eat some particular food, even those that we didn’t particularly appreciate before becoming pregnant.

Need to urinate often

In the first few weeks, the need to urinate often is linked to the increase in progesterone. Subsequently to the swelling of the uterus, which causes a compression of the bladder, a compression which entails the need to go to the bathroom more often.

However, this need should be kept in mind, it could also be due to the intake of greater quantities of liquids or diuretics, urinary tract infections, gestational diabetes .

Constipation and abdominal swelling

During the first trimester of pregnancy , constipation is quite common. Its causes can be of different nature: hormonal, food, lifestyle. Constipation can also be due to intestinal compression or  progesterone : to find out how to fight it, read here.

The conditions just described, in addition to causing constipation, can also slow down the digestive functions and favor the formation of gas and the related abdominal swelling. The same constipation can also increase abdominal swelling.


We must not forget that the first symptoms of an ongoing pregnancy are sometimes difficult to identify, as they are very subjective.

Therefore it is advisable that you speak to your trusted doctor if you think you are pregnant. He will give you all the necessary information and, where appropriate, also advice and recommendations: this article of ours is only for information and information purposes.

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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