Fourth week of pregnancy - how to confirm it and why is it still not visible on ultrasound? What is the size of the follicle at week 4 of pregnancy? Can it be seen by performing a vaginal ultrasound? Where do the bleeding come from in the 4th week of pregnancy?
The fourth week of pregnancy is the time when you can finally do a pregnancy test or ultrasound. Symptoms begin to be felt but may be easy to overlook at first. The 4th week of pregnancy is the time of embryo development - the fetus will develop from it much later.
How to know the 4th week of pregnancy?
Week 4 of pregnancy means 22-28 days (almost a full month) from your last period, not week 4 from conception. This is when your next monthly period should begin. Women who have regular cycles and pay close attention to their bodies will quickly notice if their bleeding is delayed. However, with a less regular cycle, it won't be immediately obvious.
For expectant mothers unsure of what to expect, we recommend first checking the medical facts. Discussing symptoms on an online forum often ends in panic when it turns out that some women have completely different experiences. Misunderstanding the difference between the fourth week of pregnancy and the fourth week after conception adds to the confusion.
Another problem may be irregular cycles or diagnosed polycystic ovary syndrome in women. In these cases, it is best to follow the information about the actual age of pregnancy provided by the doctor during the ultrasound of the first trimester and the following.
Fourth week of pregnancy - you can't see anything on ultrasound
The 4th week of pregnancy is the earliest moment when a gynecological examination can detect changes that indicate pregnancy , although – if possible – it is better to wait a few more weeks before visiting a doctor.
An ultrasound in the fourth week of pregnancy doesn't reveal anything about the fetus—or rather, the embryo—or changes in the uterus. Therefore, such an examination isn't always performed at that time. During a traditional gynecological examination of the vagina and uterus, the doctor can look for the first signs of changes—such as vaginal loosening under the influence of progesterone —that become apparent from the fourth week of pregnancy.
4th week of pregnancy - follicle size on a vaginal ultrasound
Even if nothing is visible on an ultrasound at this stage, it doesn't mean there's no pregnancy—it's simply too early for testing. At 4 weeks of pregnancy, the gestational sac can be located with a transvaginal ultrasound . At 4 weeks, it's less than 1 mm in size, about the size of a poppy seed, so it's impossible to see with the naked eye. However, the ultrasound image can already confirm pregnancy.
If not an ultrasound, then maybe a 4th week pregnancy test?
Since in the 4th week of pregnancy nothing is still visible on an "ordinary" ultrasound, a pregnancy test may be helpful. It is also chosen by women who are not able to visit a gynecologist immediately and cannot perform a vaginal ultrasound in the fourth week of pregnancy.
A pregnancy test, both blood and urine, checks the level of beta hCG , which is one of the two components of the hormone - chorionic gonadotropin, which is produced at the stage of implantation of the fetal egg in the uterus.
Are the tests effective in the 4th week of pregnancy?
- Most of the tests from the pharmacy detects pregnancy in a minimum 10-21 days after conception.
- Self-conducted pregnancy tests are effective in the order of approx. 90-97 percent
- Efficacy information is always on the test packaging.
- The less effective ones may have to be repeated in some time.
- You can also have a blood test from the laboratory in week 4, to find out about your pregnancy as soon as possible and with greater certainty. The level of beta hCG (chorionic gonadotropin) in the blood in normal, physiological single pregnancy should double (or increase by at least 35%) every 48 hours. As for the size of the follicle, at levels of beta hCG above 1000 mIU / mL, it begins to be visible in the uterine cavity.
Embryo (not yet a fetus) at the 4th week of pregnancy
After fertilization, the gestational sac containing the ovum, which has reached the morula stage through cell division, travels through the fallopian tube toward the uterus. During this journey, the morula develops into a blastula and then a blastocyst, before reaching its destination and implanting in the uterus, which occurs approximately 6-12 days after fertilization. From a medical perspective, it is not yet a fetus, but an embryo (embryo), because the fourth week usually marks the beginning of the embryonic development period, which is counted from the moment the ovum implants in the uterus . The embryo, which is difficult to see even on a transvaginal ultrasound at week 4, is then composed of three layers of cells – these layers will develop into various organs in subsequent stages of pregnancy.
The trophoblast, i.e. the outermost layer of cells of the fetal egg, together with the decidua (i.e. the loosened and overgrown mucous membrane) of the uterus begin to form the placenta , which, with the help of the umbilical cord, will mediate the exchange of nutrients between the mother and the child.
4th week of pregnancy - symptoms become felt
In the fourth week of pregnancy, pregnancy doesn't yet have any impact on the shape or size of a woman's abdomen, but expectant mothers experience certain discomforts at this time. The most common symptom in the fourth week of pregnancy is mild fatigue . Breasts may also become more tender than usual. Implantation of the embryo in the uterine cavity may cause mild abdominal or lower abdominal pain and minor vaginal spotting . Therefore, symptoms in the fourth week of pregnancy, as throughout the first month , are not yet very specific.
What does bleeding in the 4th week of pregnancy mean?
In the 4th week of pregnancy, spotting may occur—called implantation bleeding or bleeding, as it results from the embryo implanting in the uterine lining. This bleeding is often described online and on virtually every maternity forum, as one of the first symptoms of pregnancy a woman notices. If it manifests as light bleeding in the 4th week of pregnancy, it shouldn't cause concern for the expectant mother. During implantation, it's easy to damage the uterine lining, which can result in vaginal bleeding. It's unlikely to be confused with a period due to its short duration (a few hours), small amount of blood, and brown color. However, if stress or other ailments have caused scanty or even symbolic monthly bleeding, implantation bleeding may resemble it so closely that it's difficult to distinguish. In such a situation, bleeding at 4 weeks can make it difficult to determine the gestational age based on the date of the last menstrual period.
Consultation:
Ph.D. n. med. prof. IMID Tadeusz Issat - Head of the Obstetrics and Gynecology Clinic at the Institute of Mother and Child;
Maria Krowicka-Wasyl – resident physician during specialization in gynecology and obstetrics, Clinic of Obstetrics and Gynecology at the Institute of Mother and Child.
