Pregnancy: everything you need to know


It starts with two cells

By definition, pregnancy starts with the union of egg and sperm cells and usually covers a period of 40 weeks or 10 months after the last menstruation. The embryo or fetus, it is called from the 9th week of pregnancy, grows - protected by amniotic fluid and a thick layer of muscle - in the uterus.

He receives oxygen and nutrients from the placenta, which he is connected to via the umbilical cord, throughout his pregnancy. The placenta is not only responsible for the nutrition of the embryo, it also transports harmful and metabolic products and produces important hormones for pregnancy. These are not only important for building and maintaining the pregnancy, but also support the adaptation of the mother to the changed body situation.

After three months everything is laid out

Every month of pregnancy, there are new milestones that can be observed in a growing child. While most organs are created in the first three months, in the last three to four months, the child only grows in size and weight and is already viable outside the womb.

There is also a great deal happening with the expectant mother to provide the child with optimal conditions and to prepare for the approaching birth - a process that is not always pleasant.

Regular examinations

In order to observe the course of pregnancy and to detect possible complications that may occur in connection with pregnancy as early as possible, pregnant women in Germany are closely monitored.

At the beginning gynecological appointments take place every four weeks, from the 32nd week every two weeks; when exceeding the calculated date of birth even every two days. Overall, a pregnant woman therefore sees her treating physician about 10 to 12 times within a pregnancy.

The medical precaution covers a whole range of different examinations. In addition to the examination of blood and urine, the maternal weight development is accurately recorded and documented, take regular ultrasound examinations of the child and in the later course also CTG examinations, record the movements and heartbeat of the child and the uterine activity of the mother.

Read also:
General questions about pregnancy

Duration of pregnancy

Pregnancy weeks (SSW)

On average, pregnancy lasts 40 weeks +/- 10 days. The 40 weeks are counted from the time of the last menstruation, which corresponds to a total duration of 10 months.

To determine the exact day or the current week of pregnancy, completed weeks plus completed days of the current week of pregnancy are indicated. For example, the 5th day of the 24th week of pregnancy is described as 23 +4. So if you are on the first day of the 19th week, this is described as 18 + 0 weeks of gestation, since the 18th week is completed, but not a full day of the 19th week has ended.

Preterm birth and transmission

Premature births are children who are born before the end of the 37th week of pregnancy (<36 + 6), while birth is not referred to after the 42nd week of pregnancy.

Course of pregnancy

A pregnancy arises from the fusion of egg and sperm cell to the so-called zygote. This usually happens in the fallopian tube within 24 hours of ovulation. The zygote then migrates along the fallopian tube towards the uterine cavity and continues to divide. After about six days it comes to the implantation of the now called blastocyst cell accumulation and henceforth to the steady growth of nascent fruit.

The classification of pregnancy is classically divided into three sections of 13 weeks or about three months (trimester), in which many important events with mother and child take place.

1. First trimester

The first three months of pregnancy are characterized by a very rapid growth of the embryo and the hormonal change in the mother. This is associated with the typical pregnancy symptoms such as nausea, vomiting, cravings and fatigue. As early as the third week, the first physical changes occur, such as a slight increase in the size of the chest.

Since most departures of sonographically recorded pregnancies take place around the tenth to twelfth week, the pregnancy is usually waived during the first trimester.

a) first month (SSW 3-4)

Strictly speaking, in the first half of the first month you are not yet pregnant. Because only around the second week it comes to ovulation and fertilization of the egg through the sperm. After a 5 to 6-day migration of the zygote into the uterine cavity, the third SSW is implanted in the fruit now in the blastocyst stage. The implantation is completed after 14 days and usually takes place in the anterior or posterior wall of the uterus.

b) second month (SSW 5-8)

Between the 5th and the 8th week of pregnancy, your body gradually becomes pregnant. Triggered by the altered hormone levels and especially the beta-HCG produced by the orchard, 50-90% of pregnant women experience nausea and vomiting, fatigue, cravings or mood swings.

First heartbeats

The uterus already begins to grow and stretches the ligaments, which can lead to dull to aching pains in the abdomen and groin. In the second month, embryos already form larger organs. For example, approaches to the brain and spinal cord, but also of the head, trunk, arms and legs arise. From the 7th week, a gentle but fast heartbeat of 140-150 beats / min. be detected.

At the end of the second month, the embryo is between 9 and 15 mm long.

c) third month (SSW 9-12)

While in the third month outwardly very little of the existing pregnancy shows up, there is a lot going on within the uterus. Fine organ systems such as ears, eyes, fingers and toes form. The milk teeth are already present at the end of the third month, and the embryo moves for the first time. He now weighs 15 g and is about 50-60 mm long.

More blood, more water

To ensure optimal supply to the embryo, your blood volume increases by 1.5 liters, from about 5 liters to 6.5 liters, which makes your heart beat faster and decreases your performance. It can now increasingly come to water retention in the legs or varicose veins. The increased volume in the body can, together with the growing uterus, which increasingly presses on the bladder, lead to increased urination and increased urination.

Second trimester

a) fourth month (SSW 13-16)

When the 12th SSW is exceeded, many expectant parents have reached the point in time to announce the pregnancy. Because this is now considered stable.

By switching the production of pregnancy-sustaining hormones from the ovary to the placenta, the beta-HCG concentration in the blood is reduced and, as a rule, there is an improvement in nausea and vomiting. In very slim women is from the 13th Week also slowly off a small tummy. In addition, due to the hormonal situation, it can lead to the formation of a dark line between the navel and pubis, the so-called Linea nigra.

As a rule, you will now gain about 250 g per week, which in addition to the growth of the uterus, fetus and breasts is also due to the increased storage of water.

Boy or girl?

The fetus itself begins to grow in size and weight rapidly from the fourth month. In addition, the organ systems continue to develop, especially the lungs and the digestive system mature.

While the respiratory muscles are trained to increase their onset after hibernation, the digestive system is put into operation as early as the fourth month of pregnancy. The fetus swallows amniotic fluid, which is absorbed into the blood via its gastrointestinal tract and then returned to the amniotic fluid with the urine. During the day, the amniotic fluid is exchanged twice.

At the end of the fourth month, many parents experience an exciting aspect in the development of their child: The outer genitalia develop, the gender of the fetus becomes visible. At the end of the fourth month, the fetus is already 10 cm long and 100 g.

b) fifth month (SSW 17-20)

The fifth month marks the beginning of a symptom-free but eventful time for many pregnant women. The uterus rises to the belly button during this time, the fetus doubles or triples its weight, and often between the 18th and the 20th week the first child movements are noticeable, such as a slight tingling, the flapping of butterfly wings or a soft nudge be perceived.

The rapid growth of the uterus can cause a groin pull and back pain in the fifth month. Due to the increased need for certain nutrients, calf cramps increase during this time, and the iron level often drops noticeably.

c) sixth month (SSW 21-24)

At the beginning of the sixth month, the fetus continues to grow in size and weight. This is mainly due to an increase in the subcutaneous fatty tissue, which had been developed only rudimentary to date. Furthermore, the fetus gets fingernails and toenails and hair.

In addition to the ossification of the skeleton, the sixth month is also characterized by a rapid development of the brain. As a result, the child begins to respond to external riding such as voice, light or temperature. For example, it may be awakened by drinking cold water or being lulled to sleep by the maternal vocal sound.

At the end of the 24th week of pregnancy, the fetus measures about 25 cm and weighs about 500 g.

The best time of pregnancy

The 24th week represents another milestone for many expectant parents: From now on, there are good chances of survival for the child outside of the womb, even if they have comprehensive intensive care.

In the sixth month, many women feel very vital and fit. The uterus rises about at navel height, the breast growth continues. There are few complaints, life with baby bump can be fully enjoyed. So be sure to enjoy this part of your pregnancy!

Third Third Trimester

In the third month of pregnancy, the fetus is already well developed. He now increases in size and weight mainly and gathers strength for the upcoming birth.

For you, however, especially the end of the third trimester will be a little more exhausting again. But also the more intense, because the child his womb now leads his own life. Often the hint of a sleep-wake-rhythm is already recognizable, movements and hiccups will be more noticeable than ever.

a) seventh month (SSW 25-28)

At the end of the seventh month, the fetus weighs about 1 kg and has a length of 35 cm. He still has a lot of room to move and sometimes turns from one to the other possible birth position. He also opens his eyes for the first time and can react to specific light stimuli.

The large amount of amniotic fluid and the widening uterus puts pressure on surrounding organs, so that your lungs, for example, can no longer expand properly and cause shortness of breath. The stomach also has less space, resulting in a faster feeling of satiety. Pressure on the lower back risks sciatica and the development of hemorrhoids. Especially in the summer there are still some significant water retention in the arms, hands, legs and feet.

b) eighth month (SSW 29-32)

Even in the eighth month, the child continues to grow in size and weight, so it is about 40 cm long at the end of the 32nd week of pregnancy and weighs up to 1700g. Pregnant women may already have their first labor contractions. Exercise labor, also referred to as foreshortening, is a first, painless contraction of the uterus. Preparatory labor arises spontaneously, but can also be provoked by stress or physical exertion. This is then a signal from the body to slow down a bit and get more attention again.

Due to the altered ph-level pH, this month you are also particularly prone to fungal or bacterial mucosal infections.

c) ninth month (SSW 33-36)

Four to six weeks before birth, the abdomen slowly lowers. This means that the child's head settles in the small pelvis and thus the child goes into the birth position. If the head lies in the small basin, it is almost impossible for the child to turn again. In addition, the space in the womb is becoming more limited by a further increase in size and weight.

About 93% of all unborn children are in the ninth month with the head in the pelvis and thus in optimal birth position, the cranial position.

The belly begins to lower

From the 35th week of pregnancy, the last maturation process, the lung maturation of the child, is completed. The child is about 45 cm long at the end of the ninth month and weighs just under 3 kg.

By lowering the abdomen your stomach and your lungs get more space again, so that breathing and food intake are easier. In the ninth month, many women experience sleep disturbances that can be viewed as a preparation for a child's nights.

d) tenth month (SSW 37-40)

By the end of pregnancy, you will have gained an average of 10-15 kg in weight. Shortly before birth, many pregnant women experience stagnation in weight gain or even a slight weight loss. Punches now occur with greater regularity and can already cause a slight pull.

In the last four weeks of pregnancy, the child gains weight up to 300 g per week, so at the end of the pregnancy it weighs between 3 and 4 kg and is around 50 cm long. The diameter of the child's head is about 10 cm.

4th birth

The pregnancy ends with the birth of the child at the 40th week after the last menstrual period. Only about 3-4% of all babies come to the world, most babies are born in the period from about 10 days before to 10 days after the appointment.

In many expectant mothers, the approaching birth announces certain symptoms.These include, among other things, the departure of a bloody-tinged mucus plug (so-called drawing bleeding), vomiting, nausea or diarrhea, or even the bursting of the amniotic sac (so-called premature rupture of the bladder).

After the onset of the first cervical labor until the birth of the child on primary care on average by 12 to 14 hours pass, the first 12 hours serve by opening labor opening the cervix to about 10 cm and the remaining 1 to 2 hours of expulsion of the child by means of press swelling.

Good to know:
Frequently asked questions at the time of pregnancy

pregnancy tests

The determination of pregnancy can be done in different ways. The most common method is the pregnancy test, which can be done by yourself. This measures a specific hormone in the urine, the so-called beta-HCG, which is produced by the growing fear in the womb and occurs especially in concentrated morning urine in larger quantities.

Discoloration of both stripes = pregnant

Common pregnancy tests are available at the pharmacy or drugstore and can only be used after the rule has been missed. After the test strip of the pregnancy test has been wetted with urine, it indicates the result within 40 seconds to 10 minutes.

Simple tests consist of two strips, both of which stain in the event of pregnancy. More modern test variants can already indicate the pregnancy week relatively accurately on a digital display field.

For safety to the gynecologist

Conventional pregnancy tests, if used correctly, are relatively safe. On the other hand, it is different with early tests, which can be carried out a few days before the expected menstruation. These tests provide more false-negative results more often, which means that there is a pregnancy, although the test indicates a negative result.

But even traditional tests can rarely be false-negative or false-positive. Therefore, it is useful and important to visit a gynecologist in case of a reasonable suspicion of the existence of a pregnancy. In addition to another urine test, this will carry out a vaginal ultrasound examination of the uterus and, if necessary, withdraw blood in order to confirm or rule out pregnancy in case of doubt.

More about this topic can be found here:
Pregnancy Diagnosis

Determination of the delivery date

After fertilization of the maternal oocyte, pregnancy lasts plus / minus 40 weeks from the time of the last period. The gestational age or the delivery date can be determined by calculation or by ultrasound examination.

The date of birth is important in so far as he provides guidelines for each examination of pregnancy, how big and how difficult the child and / or what should have developed piece by piece.

1. Computer determination

The mathematical determination of the date of birth is the most common method for estimating the gestational age. Many calculators that can be retrieved online are based on it.

There are differences between:

  • Simple Naegele Rule: The prerequisite for using the simple Naegele Rule is that your cycle must be exactly 28 days long. If this criterion applies, the due date is calculated as follows: First day of the last menstrual period + 7 days - 3 months + 1 year. For example, if your last menstrual period was on April 9, 2018, the probable delivery date will be January 16, 2019.
  • the extended Naegele rule: The extended Naegele rule is applied when your cycle is longer or shorter than 28 days. The difference to the 28 days will be included in the calculation when expanding the rule: First day of the last menstrual period + 7 days - 3 months + 1 year +/- Deviation of your cycle from the regular 28 days. For example, if you have a cycle of 27 days and the last period was 09/04/2018, the due date is calculated as follows: 09.04. + 7 days - 3 months + 1 year - 1 day and would be on 15.01.2019

The Naegele rule provides the day on which the greatest birth probability is to be expected. In fact, only about 3% of all children are born on the calculated date. Still, births are considered as premature births up to three weeks before and two weeks after the calculated date, which is about 90% of all births.

2. Determination by ultrasound examination

The ultrasound examination of the embryo takes place approximately until the 12th week of vaginal ago, after the 12th week then through the abdominal wall. Depending on the age or size of the embryo different measurements are used to determine the date of birth:

  • largest length: The largest extension of length of the embryo can be used only in very early stages for the calculation of the delivery date. It is the largest expansion of the first plants used.
  • Crown-Rump Length: When calculating crown-rump length, measure the length from the beginning of the crest of the embryo to the lowest point of the rump. This method can be used from the 6th to the 12th week and provides a relatively good assessment.
  • Crown Heel Length: From the heel to the heel, the survey can be made from the 12th week.Due to the joint positions, however, a precise calculation is difficult and very prone to error, and thus more unreliable than the estimation of the birth date from the crown-rump length.

Although they are still trends and not exact dates, the ultrasound-assisted assessment of the delivery date is more accurate than the results obtained with the Naegele rule.

signs of pregnancy

Pregnancy signs are changes in the female body that provide evidence of an existing pregnancy. There are unsafe and safe pregnancy marks.

Unsafe pregnancy marks

Uncertain signs of pregnancy are understood to mean changes in the female body, often in connection with pregnancy. But the signs can also have a different cause, which is why they are no sure proof that you are pregnant or not.

Unsafe pregnancy marks include:

  • Absence of the menstrual period
  • especially morning sickness and vomiting
  • Tension and increase in size of the breasts
  • Dark colouration of the nipples
  • livid discoloration of the vagina or vaginal entrance
  • fatigue
  • mood swings

Safe pregnancy marks

Safe pregnancy marks, in contrast to the uncertain ones, are evidence of pregnancy. In principle, they can be considered as objective evidence of a living embryo or child in the womb. Safe pregnancy marks include:

  • Beta HCG detection from blood serum or morning urine (possible from 4th to 5th week of pregnancy)
  • Proof of an embryonic implantation in the uterine cavity by means of vaginal ultrasound examination (from the 5th to 6th week of pregnancy possible, with evidence of cardiac actions only from the 7th week can be seen)
  • Detection of children's heart sounds using Doppler sonography (possible from the 12th week of pregnancy)
  • Perception of child movements (from 18th to 22th weeks possible)
  • Proof of cardiac tone in the cardiotogram (CTG), (from the 24th week possible)

Changes in the female body

Without pregnancy sexually mature women have menstruation every 25 to 31 days. Under the influence of estrogens, the uterine lining subsequently rebuilds and an egg cell matures in one of the two ovaries.

Around the 12th to 14th day after the period ovulation then takes place. In the ovary in question remains the corpus luteum, quasi the shell of the cracked ice, which produces from now on for about 10 days progesterone. Under the influence of this hormone, the body adjusts to a possible pregnancy.

Progesterone and other hormones

If the ovum is not fertilized or does not nest after fertilization, Progesterone levels drop after just two weeks and menstruation begins. However, if it comes to fertilization and implantation of the fusion product of egg and sperm cell, the progesterone production is continued by the corpus luteum and pregnancy thus obtained.

In addition to progesterone there is an increase in a variety of other hormones whose function is briefly explained below:

  • Beta HCG: HCG is mainly formed in early pregnancy by the developing placenta. It stimulates the corpus luteum of the ovary to continue its progesterone production and thus contributes significantly to the maintenance of pregnancy. Furthermore, HCG is held responsible for many of the pregnancy symptoms that occur in the first few weeks, such as nausea and vomiting, fatigue and malaise. HCG reaches its maximum concentration around the 10th week and then drops off continuously.
  • Progesterone: The first 10 weeks of pregnancy, progesterone is produced by the corpus luteum under the influence of beta-HCG. Subsequently, the placenta takes over the production of progesterone, whose concentration increases during the entire pregnancy. In addition to maintaining pregnancy by creating optimal conditions in the uterus, it also serves to increase breast tissue and secretion of breast milk. Shortly before birth, together with the hormone oxytocin, it is also important for promoting labor.
  • Estrogen: Similar to progesterone, the concentration of estrogen increases throughout pregnancy. The estrogen works synergistically with progesterone and helps build the uterus and prepare the breast for milk production.
  • Glucocorticoids: Glucocorticoids such as cortisone are formed by the adrenal cortex of the mother and are mainly used for the lung maturation of the child from the 24th week. An unfavorable side effect of glucocorticoids is that they can weaken the tissue and promote the development of stretch marks.
  • Thyroid hormones: In pregnancy there is a slight increase in thyroid hormones, which is very important for the development of the embryo's brain and spinal cord. Increased hormone production may cause the thyroid to swell slightly during pregnancy.
  • Prolactin: The steady increase in estrogens causes the production of prolactin at the end of pregnancy.This hormone is especially important after pregnancy, as it is responsible for the differentiation of the mammary glands and stimulates the breast to milk.
  • Oxytocin: Oxytocin is released by the maternal pituitary at the end of pregnancy. It has two very important effects. On the one hand, it promotes the contraction of the uterine musculature and is thus decisively responsible for the onset of labor; on the other hand it serves the mother-child-bond.


For many women, diet is an important issue during pregnancy. The credo that a pregnant woman has to eat for two is long outdated. While the average recommended number of calories per day in non-pregnant women is around 2000 kcal, in the first trimester of pregnancy it only rises by about 100 kcal and is about 2500 kcal per day from the 4th month of pregnancy.

Increase depending on the starting weight

The weight gain during pregnancy varies greatly from woman to woman. Based on your BMI can be roughly estimated how much weight you should gain during pregnancy optimally:

  • BMI <18.5 (underweight): recommended weight gain about 12.5-18 kg
  • BMI 18.5-24.9 (normal weight): recommended weight gain about 11.5-16 kg
  • BMI 25.0-29.9 (pre-obesity): recommended weight gain about 7-11.5 kg
  • BMI> 30 (obesity): recommended weight gain about 5-9 kg

Important vitamins and trace elements

While little changes in the calorie requirement during pregnancy, the need for certain Vitamins and trace elements increases significantly. Therefore, these should be taken before and during pregnancy in the form of dietary supplements:

  • folic acid
  • iodine
  • iron
  • Vitamin B12
  • calcium

Mixed preparations with the right composition of the individual vitamins and trace elements of the listed substances are available in the pharmacy without prescription and partly tailored to the respective trimester of pregnancy.

Wash everything well and cook through

What foods you eat during your pregnancy depends on your cravings - exact guidelines on what you should and should not eat do not exist. However, the Robert Koch Institute makes some recommendations regarding nutrition in pregnancy, which should reduce the risk of infection, especially with toxoplasmosis and dietary Listeria.

Toxoplasmas and Listeria are germs that enter the body via food and, especially in early pregnancy, can cause damage to the child. To protect yourself, you should avoid unwashed and uncooked foods and avoid the following products:

  • Raw milk products such as raw milk cheese or raw fish, as these products may be dangerous for listeriosis
  • raw meat, since toxoplasma can accumulate here. Even in cat feces, the risk of toxoplasmosis lurking, so you should abstain from cleaning the litter box during pregnancy.

Read also:
Nutrition in pregnancy

Author: Lisa Wunsch


Kirschbaum et a .: Checklist Gynecology and Obstetrics, Thieme Verlag, 2005.

Goerke et al .: Clinical Guide Gynecology and Obstetrics, Urban & Fischer, 2010.

Robert Koch Institute: Listeriosis,, last accessed on 19.04.2018.

Robert Koch Institute: Toxoplasmosis,, last accessed on 19.04.2018.

Joint Federal Committee: Guidelines on medical care during pregnancy and after delivery: pdf, last accessed on 19.04.2018.