This is the first post in our special “Pregnancy week by week” series.We want you to join us on this adventure that will show you the wonder of human gestation and will conclude with the birth of the baby. But we begin before conception, because it is considered the The first day of menstruation is considered the beginning of pregnancy. (although in the first two weeks: menstruation and ovulation, there is no pregnancy yet); and it is the classic reference for calculating the Probable Due Date.
Week 1 of pregnancy: what's really happening in your body
El first day of menstrual bleeding This is considered the first day of a woman's menstrual cycle. This cycle lasts approximately 28 days, although cycles lasting between [number of days] and [number of days] are considered normal. 24 and 35 daysWhen a woman has regular cycles, it's possible to calculate the time of ovulation more accurately, but in most cases this is complicated. Calculating the exact date of ovulation or fertilization is practically impossible; therefore, the timing of conception is still considered... first day of the last menstruation like the first day of pregnancy, even knowing that, most likely, during the first two weeks you are not yet pregnant.
Internally, this first week sees the periodThe woman begins a new cycle with bleeding that usually lasts between 3 and 7 daysdepending on the type of cycle each woman has. During these days, pituitary hormones FSH and LH They are beginning to prepare to be secreted again and, as a result, the ovary will soon begin to develop new follicles and secrete sex hormones such as estrogen.
Thanks to the release of estrogens from the ovaryThe endometrium (the inner lining of the uterus) will proliferate again and begin to thicken once menstruation has ended. In women with very short or irregular cycles, the Ovulation may occur earlier than usual and even during this first week, so they could get pregnant if they have unprotected sex, although it is not the most common thing.
The symptoms you notice at this stage are those typical of menstruation: bleeding, abdominal pain, discomfort in the lower back or pelvic area, feeling of tiredness and even mood swings. These signs are similar to premenstrual symptoms, so there's still no way to distinguish a possible future pregnancy based solely on physical sensations.
What happens in the uterus and why does menstruation occur?
From this one first day of the last menstruation a whole cycle of changes begins Physical, hormonal, and psychological factors aimed at achieving pregnancy and, if it occurs, a successful outcome. Menstrual bleeding occurs due to the desquamation, shedding and expulsion of the endometrium that had been prepared in the uterus to receive the fruit of fertilization and that, finally, since this did not occur, is no longer useful.
This endometrial tissue, rich in blood vessels and nutrients, is removed so that the body can “clean” the inside of the uterus and begin preparing its cavity again to receive an embryo in the coming weeks if fertilization occurs. After menstruation, the endometrium gradually thickens again and becomes a suitable environment for possible implantation.
In this first week of pregnancy (counted in gestational weeks), The implantation of the embryo has not yet occurredTherefore, any pregnancy test you take these days will be negative. Urine tests don't usually show a positive result until at least [date missing]. 10-14 days after fertilizationThat is why it makes no sense to take a pregnancy test the day after or a few days after having sex.
Start preparing your body: care before conception
If our intention is to seek pregnancy, we should start preparing From this moment on, even if fertilization has not yet occurred. This stage is known as preconception period And it's key for your health and the health of your future baby. It's a good idea to review your habits, diet, weight, exercise, medication, and any pre-existing conditions.
It is important to take a vitamin supplement based on folic acidIdeally, vitamin B12 intake should begin at least three months before pregnancy, as this B vitamin helps reduce the risk of neural tube defects in the baby, which form in the first weeks of gestation, when many women are not yet aware they are pregnant. Guidelines typically recommend a daily intake of at least... 400 micrograms of folic acidHowever, the dose may be adjusted according to your situation and medical criteria.
In addition to folic acid, the following are increasingly considered important: iodo At this stage, iodine requirements increase during pregnancy, and a deficiency has been linked to problems in the baby's neurological development. Therefore, many women begin a combined folic acid and iodine supplement From the moment they decide to abandon contraceptive methods, always under professional supervision.
Our lifestyle and dietDo not drink alcohol, use tobacco, or take drugs. Tobacco has been linked to a higher risk of miscarriage, premature birth, and respiratory problems in newborns, while alcohol can cause serious developmental problems in the fetus. The safest option is a zero consumption of tobacco, alcohol and other toxic substances from the moment you start planning your pregnancy.
Regarding diet, take a varied and balanced diet Based on fruits, vegetables, whole grains, legumes, fish, lean meat, and eggs. Increase your consumption of products rich in calcium and iron and limit caffeine (coffee, tea, energy drinks), as it can interfere with iron absorption, a key nutrient for preventing anemia. Also, begin implementing food safety measures against toxoplasma and listeriaWash fruits and vegetables well, cook meats thoroughly, avoid raw seafood, uncooked cured meats, or cheeses made with unpasteurized milk.
Take the moderate exercise Regular exercise, such as walking, swimming, or practicing yoga specifically designed for fertility or early pregnancy, can improve circulation, help manage weight, and reduce stress. Physical activity should be adapted to your fitness level, avoiding high-impact or very intense exercises if you are not used to them.
If you drink hormonal contraceptivesIt's important that you stop taking them and wait until you have a normal period (depending on the woman, one or two periods) before trying to get pregnant. This will make it easier to calculate the date of your last period and the gestational age, and your endometrium will have returned to its natural cycle.
Preconception consultation: why the medical check-up is so important
It is very useful to arrange a visit your doctor and your midwife; a preconception consultation will be very importantIn it, they will perform a cytology and blood tests to find out your current condition, check iron levels, vitamins, thyroid function, and rule out any infectious diseases you may have had or that need to be prevented.
If you take any chronic medication This review is even more important. Some medications are not compatible with pregnancy and it may be necessary to replace them with others that are safer for the baby, adjust the dosage, or even discontinue them. Conditions such as diabetes, high blood pressure, autoimmune diseases, epilepsy, thyroid disorders, or a history of thrombosis They require a specific assessment with a specialist to determine the best time to get pregnant and the most appropriate follow-up plan.
This visit is also the time to carry out the diagnostic tests These tests may not be possible or may be restricted later on, such as some X-rays or imaging tests using ionizing radiation. If you have recently had X-rays or a CT scan, discuss this with your healthcare professional so they can assess whether specific follow-up is necessary.
must not forget the oral healthCheck your gums and teeth before trying to conceive, as hormonal changes can increase the risk of gingivitis and other infections that, if left untreated, could affect your pregnancy. Proper dental hygiene and annual checkups are essential for good oral health and well-being.
Emotional health, sexuality and how to live this first week
Although strictly speaking there is no embryo yet, for many women week 1 marks the emotional beginning of pregnancy. It's common to feel a mixture of hope, fear, and doubtGetting information from reliable sources, attending support groups or pregnancy classes, and sharing your concerns with your partner or trusted people can help you experience this stage with more peace of mind.
In the absence of medical contraindications, the sexual intercourse They are completely safe at this stage and, in addition, they benefit well-being thanks to the release of endorphins. If you are trying to conceive, it is helpful to know your fertile windowSperm can survive for up to five days in the female reproductive tract, while the egg lives for approximately 24 hours. Therefore, the period of peak fertility extends from about five days before ovulation until one day after.
Take care of rest and stress management Getting enough sleep, establishing relaxing routines, and engaging in enjoyable activities (reading, walks, mindful breathing) are also part of this preparation. These activities help maintain hormonal balance and improve your quality of life while trying to conceive.
And now remember that next week we will return with a new delivery to continue supporting you every step of the way during this very special time.
Image - Robert McDon.
This first week is a key starting point: even though there isn't a baby on the way yet, your body is already resetting and preparing, and every decision you make regarding diet, lifestyle, medical check-ups, and emotional care can make a positive difference to your future pregnancy.