Maternal and fetal status at 15 weeks of pregnancy
Generally referred to as the stable period, the 15th week of pregnancy is said to be the time when the placenta stabilizes, the risk of miscarriage decreases, and morning sickness subsides. In addition, as the fetus grows, the uterus also grows, so this is the time when the belly begins to swell noticeably. The important organs of the fetus have also finished forming, and this is also the time when an ultrasound examination can be used to determine the baby’s gender and whether it has Down’s syndrome (trisomy 21) during prenatal checkups.
Condition of a pregnant woman at 15 weeks
The 15th week of pregnancy is when the first trimester ends and the baby moves into the second trimester. By the 15th week of pregnancy, the placenta is complete and stable. This is also called the stable period, and the pregnant woman’s morning sickness subsides, and many women have regained their appetite and are worried about gaining weight.
In addition, the uterus grows as the fetus grows. At 15 weeks pregnant, your belly starts to swell and it is said that others will start to notice your pregnancy.
Hormones are the main cause of back pain during pregnancy
During the 15th week of pregnancy, the amount of blood required by the fetus increases, causing many pregnant women to suffer from swelling. In addition, a hormone called relaxin is secreted from early pregnancy, which relaxes the ligaments throughout the body, including the pelvis, so that the baby can pass through the birth canal smoothly during birth. Relaxin relaxes the ligaments, putting strain on the muscles around the joints, making it easier for joint pain, such as back pain, to occur.
In addition to joint pain, many pregnant women suffer from frequent urination due to the pressure on the bladder caused by the enlarged uterus. For this reason, many women refrain from going out or exercising even though they have entered the stable period. In order to maintain your health and change your mood during pregnancy, you should consult with your own physical condition and take up walks and light stretching to promote blood circulation.
Pregnancy gingivitis and the risk of premature birth
During pregnancy, female hormones change significantly. This causes a decrease in saliva production, which in turn causes the proliferation of periodontal disease and caries (tooth decay), which are normally prevented by saliva, and is thought to lead to pregnancy gingivitis.
Pregnancy Gingivitis often causes red, swollen gums and bleeding. In particular, oral bacteria called Porphyromonas Gingivalis (PG bacteria) is said to increase the risk of premature birth as well as gingivitis.
PG bacteria that not only cause gingivitis but also raise blood sugar levels
Porphyromonas Gingivalis (PG bacteria) is also known as the “blood-sucking bacteria” and the “most frightening oral bacteria.” When Pg bacteria proliferate in a pregnant woman’s mouth, they invade the bloodstream, grow in the body, and reach the uterus, causing immune cells to react. This increases hormones that cause uterine contractions, which is said to cause premature birth.
Pj bacteria are oral bacteria that not only cause gingivitis, but also raise blood sugar levels and cause blood clots. Previous research has also shown that they may affect dementia. For these reasons, they are feared as the most frightening oral bacteria, but Pj bacteria can be prevented by regular dental checkups and proper, careful brushing of the teeth.
Many pregnant women have severe morning sickness and find it difficult to brush their teeth during pregnancy. If you are 15 weeks pregnant and your morning sickness has subsided, be sure to brush your teeth carefully, and if you notice bleeding gums or unusual bad breath, consult a dentist as soon as possible.
Baby’s condition at 15 weeks pregnant
At 15 weeks pregnant, the average size of a baby is about 10cm in crown-rump length (from head to buttocks) and the average weight is about 100g. At 15 weeks pregnant, the baby’s organs are formed and its muscles develop. The baby will start to move its arms and legs inside the mother’s womb, but because its body is still small, you may not feel it as fetal movement. It is said that it is only after the 27th week of pregnancy that the position of the fetus and the position of its head can be felt from above the stomach.
This is the time when the eyes and eyelids are formed, but the visual system is not yet fully developed. On the other hand, the ears also begin to form, and although the hearing system is not yet fully developed, this is the time when the ossicles that transmit sound vibrations begin to form.
Ultrasound photo taken at 15 weeks of pregnancy.
What an ultrasound scan at 15 weeks pregnant reveals
Ultrasound examinations performed as part of prenatal checkups are transvaginal ultrasounds from weeks 4 to 11 of pregnancy, and from the 12th week onwards they become abdominal ultrasounds, which are performed using ultrasound from above the abdomen.
At 15 weeks of pregnancy, the baby’s external genitalia are formed, and it is often possible to determine the gender of the baby by the position of the baby’s body using an ultrasound examination. However, some medical institutions may not tell you the gender results of the ultrasound examination, so it is a good idea to check in advance.
Down syndrome detected by ultrasound at 15 weeks
Down syndrome is a chromosomal abnormality that occurs when there is an extra 21st chromosome, making a total of three copies. It is said to be the most common chromosomal abnormality, and the probability of Down syndrome (trisomy 21) increases with increasing gestational age.
In order to check for the presence of Down syndrome (trisomy 21) in the fetus during pregnancy , prenatal diagnosis is required. One such test is an ultrasound examination, which is included in prenatal checkups, and an ultrasound is used to determine the physical characteristics of Down syndrome (trisomy 21) in the fetus.
When can Down Syndrome be detected by ultrasound?
“From when can Down syndrome be detected by ultrasound?” ” When can Down syndrome be detected by ultrasound?” These are questions we receive frequently from pregnant women during prenatal checkups. It is said that the possibility of Down syndrome (trisomy 21) can be determined by ultrasound examination from the 11th week of pregnancy onwards, when the fetus has grown and appropriate observation is possible.
Characteristics of Down Syndrome as Determined by Ultrasound Examination
Swelling at the back of the fetus’s neck
One of the characteristics of Down syndrome (trisomy 21) that can be seen on an ultrasound examination at 15 weeks of pregnancy is a “swelling” at the back of the fetus’s neck. This is called “Nuchal Translucency (NT)” or “fetal posterior cervical subcutaneous transparent area.”
Swelling of the subcutaneous tissue at the back of the neck is a physiological phenomenon seen in all fetuses during the early stages of pregnancy. However , in the case of Down syndrome (trisomy 21) , the swelling at the back of the neck increases from early to late pregnancy, and the frequency of fetuses with chromosomal abnormalities and abnormalities in cardiac function is said to increase.
Head Shape
If the fetus has Down syndrome (trisomy 21) , the facial angle tends to be larger than normal, and the head tends to be shorter in height than in width. Normally, as the fetus’s face grows, the width of the face decreases, but in the case of Down syndrome (trisomy 21) , this characteristic becomes more pronounced as the fetus grows.
Nose Shape
During an ultrasound examination, the characteristic shape of the nose is also considered one of the factors that can determine whether or not a child has Down’s syndrome (trisomy 21) . In the case of Down’s syndrome , the growth of the nasal bone is delayed, resulting in a low base of the nose and a flat facial appearance. However, since there are also genetic factors, it is not possible to determine whether or not a child has Down’s syndrome (trisomy 21) based on the shape of the nose alone.
Backflow of blood
Complications of Down syndrome (trisomy 21) include heart disease, and an ultrasound examination may show backflow of blood in the fetus.
How to read ultrasound images
Depending on the medical institution that performs the prenatal checkup, some pregnant women may be able to receive ultrasound images. However, the ultrasound images have a series of alphabets on them, and many pregnant women may not know what they mean. The meanings of the alphabetical abbreviations on ultrasound images are as follows:
EDC/GA
EDC: expected delivery date/GA: gestational age
EFW
Estimated fetal weight
SD
Standard deviation: An index of how far the fetal size differs from the standard value
AFI/AFP
AFI: Amniotic Fluid Index/AFP: Amniotic Fluid Pocket (both are indicators of amniotic fluid volume)
How to detect Down syndrome in a fetus without using an ultrasound
Prenatal ultrasound examinations are an important part of prenatal checkups to determine the baby’s health before birth. At the same time, ultrasound images are an important record that allows you to see the growth of your baby in the womb.
Ultrasound examinations are only used to check the physical characteristics of the fetus, and can only determine whether or not there is a possibility of Down syndrome (trisomy 21) . In addition, there are many congenital diseases caused by chromosomal abnormalities that cannot be detected by ultrasound examinations.
NIPT (New Prenatal Testing) can detect Down Syndrome from about 6 weeks of pregnancy
Down syndrome (trisomy 21) can be detected by ultrasound examination from the 11th week of pregnancy onwards. Also , since ultrasound examination is a test to confirm the physical characteristics (shape abnormalities) of the fetus, it is not possible to evaluate chromosomal abnormalities of the fetus that cannot be detected by visual inspection. On the other hand, NIPT (non-invasive prenatal testing) is said to be able to check for chromosomal abnormalities of the fetus from about the 6th week of pregnancy.
NIPT (new type prenatal testing) is a prenatal test with no risk of miscarriage
NIPT (non-invasive prenatal testing) is a prenatal test that is performed by simply taking a blood sample from the mother. As it is called a non-invasive prenatal genetic test, it is said that there is no direct invasion (damage) to the fetus.
NIPT (non-invasive prenatal testing) is a screening test that evaluates the possibility of a fetus having a chromosomal abnormality with a “positive” or “negative” result. However, when it comes to Down syndrome (trisomy 21), it is considered to be a highly accurate test with a sensitivity and specificity of 99.9%.
For these reasons, pregnant women who are unsure about the diagnosis of Down syndrome (trisomy 21) based solely on an ultrasound examination may want to consider NIPT (non-invasive prenatal testing).
Summary
Down syndrome (trisomy 21) is considered to be the most common chromosomal abnormality. In many cases, the possibility of Down syndrome (trisomy 21) is diagnosed by ultrasound examination during prenatal checkups, but there are many congenital diseases caused by chromosomal abnormalities that cannot be detected by ultrasound examination alone. In addition, going through pregnancy without noticing a chromosomal abnormality in the fetus carries the risk of miscarriage or premature birth, which can have a significant impact on the health of not only the fetus but also the mother.
NIPT (New Prenatal Testing) is a prenatal test that can be performed from about 6 weeks of pregnancy. It can detect the risk of congenital diseases caused by chromosomal abnormalities in the fetus earlier than ultrasound examination. In addition, Hiro Clinic NIPT not only tests for Down syndrome (trisomy 21) alone, but also tests for all chromosomes.
If you are a pregnant woman who has questions about Down syndrome (trisomy 21) or NIPT (non-invasive prenatal testing) , or if you are worried about the testing plan, please consult with the NIPT staff at Hiro Clinic . Let’s have a healthier pregnancy with the optimal NIPT (non-invasive prenatal testing) plan.
【References】
- Japanese Society for Bacteriology – Oral bacteria (Porphyromonas gingivalis)
- Health direct, Department of Health, Australian government – Pregnancy at week 15
- Holly Pevzner. Verywell family, – Week 15 of your pregnancy
- Ministry of Health, Labor and Welfare – Mid-pregnancy
- J. Women’s Health Jul;25(7) 672-9 (2016) Cheng E. et al. – The influence of antenatal partner support on pregnancy outcomes.
Article Editorial Supervisor
Dr Hiroshi Oka
NIPT specialist clinic, MD
Graduated from Keio University, School of Medicine
