Examining multiple elements is necessary to comprehend how your unborn child is growing during pregnancy, and placenta thickness is one of those elements. Your baby receives vital oxygen and nutrition from the placenta, which also eliminates waste. The placenta’s thickness varies as your pregnancy goes on, and monitoring these changes can provide you with important information about the health of your unborn child.
We’ll examine how the placenta’s thickness changes over the course of a pregnancy in this article. We’ll talk about the significance of the measurements and how they might affect your pregnancy. You can feel more prepared and informed as you proceed through each exciting phase of this amazing journey with the aid of this information.
Knowing the thickness of the placenta can be a useful component of your prenatal care, regardless of whether you’re a first-time mother or have experience with pregnancy. Let’s explore the information you should have to guarantee the health of both you and your child.
Doctors monitor the placenta’s thickness every few weeks during pregnancy to ensure that it is growing properly and supplying the baby with nutrients. It is a key indicator of the health of both the mother and the unborn child. As a pregnancy goes on, the placenta usually thickens; therefore, any deviations from the typical range may indicate possible complications. Expectant parents can gain a better understanding of what to expect during prenatal checkups and why placenta thickness is important for a healthy pregnancy by knowing how it changes throughout each stage of pregnancy.
Structure and functions
The placenta is a transitory organ that is only required for childbearing. It maintains a tight bond between the mother and the developing fetus by serving as a middleman in the most critical functions for the baby’s growth, including gas exchange, nutrition, and waste product elimination. The baby receives blood from the mother that is enhanced with oxygen, vitamins, minerals, and water through the uteroplacental blood flow. Through the placenta, carbon dioxide, creatinine, and urea are expelled again.
The placenta is a “factory” of hormones necessary for the successful bearing and birth of a child. It produces hCG, progesterone, estrogens, placental lactogen. Without a sufficient level of these hormones, it will not be possible to bear a baby, and breastfeeding will be in great question. The placenta begins to form after the implantation of the fertilized egg into the uterine cavity. Usually this occurs on the 8-9th day after ovulation, if the egg is fertilized. At first, the appearance of the placenta is preceded by the chorion, thanks to which the blastocyst attaches to the functional layer of the uterine endometrium. Gradually, the chorion grows, new layers appear, and by the 14-16th week of pregnancy, the young placenta begins to perform its functions.
The placenta stops growing and starts to mature or age at the middle of the second trimester, when the "baby’s place" continues to grow and thicken. The placenta typically reaches zero maturity until the thirty-first week, at which point calcium salt deposits start to form and the placenta becomes denser. First degree up until the 34th week of pregnancy; second degree thereafter (almost until delivery). The third degree is measured soon before delivery (in a typical pregnancy), signifying that the placenta has nearly used up all of its resources and abilities.
Norms
There is no diagnostic value to the placenta’s thickness until the twentieth week of pregnancy. The location of the attachment and the "baby’s place" are established by ultrasonography; the thickness won’t be measured until the 20th week. The placenta’s thickest region will be measured by the ultrasound sensor, and this is the indication that is thought to be most important. It matters if the thickness matches the recommended values for the gestational age at this time. The table below lists the norms.
Here is a table of placenta thickness by week.
| Gestational age, (weeks) | Placenta thickness (range of normal values), mm |
| 20 | 16.7–28.6, usually – 21.9 |
| 21 | 17.4–29.7, on average – 22.8 |
| 22 | 18.1–30.7, on average – 23.6 |
| 23 | 18.8–31.8, on average – 24.5 |
| 24 | 19.6–32.9, usually – 25.3 |
| 25 | 20.3–34.0, usually 26.2 |
| 26 | 21.0–35.1, usually 27.0 |
| 27 | 21.7–36.2, on average 27.9 |
| 28 | 22.4–37.3, on average 28.7 |
| 29 | 23.2–38.4, on average 29.6 |
| 30 | 23.9–39.5, usually 30.5 |
| 31 | 24.6–40.6, usually 31.3 |
| 32 | 25.3–41.6, usually 32.1 |
| 33 | 26.1–42.7, on average — 33.0 |
| 34 | 26.8–43.9, on average — 33.8 |
| 35 | 27.5–45.0, on average — 34.7 |
| 36 | 28.0–46.1, on average — 35.5 |
| 37 | 27.8–45.8, usually — 34.3 |
| 38 | 27.4–45.5, usually — 34.0 |
| 39 | 27.1–45.2, usually — 33.7 |
| 40 | 26.7–45.0, usually — 33.4 |
The numbers displayed are averages. In actual practice, there might be slight departures from the recommended norms; in each case, the physician makes a well-informed decision based on the particulars of the patient and the pregnancy. Nevertheless, noticeable variations greater than tenths of a millimeter need closer inspection. A placenta that is abnormally thin—its thickness should not exceed 20 mm—or thick—it should not exceed 5 cm.
It is usually decided to wait and watch if there are no other pathologies or pregnancy complications in addition to the placenta’s thickness, which does not match the terms. The placenta may have unique structural characteristics, but if their thickness has no effect on how the "baby’s place" works, then there’s no need to worry.
Causes and consequences of deviations
A placenta that is extremely thin or thick is one of two types of deviations from the norm. Both are risk factors because abnormalities in the "baby’s place"’sstructureinterfere with its functions, which are directly related to the development and well-being of the infant. It is important to carefully analyze both circumstances.
Thick
Hyperplasia of the placenta is spoken of when the thickness of the "baby"s place" is higher than the upper limit of the permissible range of normative values. The greater the difference, the more serious the situation. A thick placenta alarms doctors much more than a thin one, because with hyperplasia, the temporary organ ages faster, matures, and this is fraught with premature birth, fetal hypoxia, fetoplacental insufficiency and delayed development of the baby. If the placenta ages prematurely, the baby in any case does not receive enough oxygen, vitamins and nutrients. It may show symptoms of intoxication of the body, because the placenta copes worse and more slowly with the removal of waste products. There are a lot of reasons that can cause hyperplasia. This, for example, diabetes mellitus in a future mother. With it, not only thickness is violated, but also the structure of the placenta – an additional lobe may be present.
Some pregnant women experience chronic anemia in the early stages of pregnancy, which can increase the thickness.
A woman has a very high chance of developing placenta hyperplasia if she contracted a virus early on (like SARS or influenza). "Children’s Place" can respond to sexually transmitted infections, genital tract infections, and "winged" infections (chlamydia, ureapaplasmosis, and others) with a thickening. If a Rh-negative mother is carrying a Rh-positive child, a Rh conflict may cause the placenta’s thickness to increase at any point during pregnancy, leading to sensitization. Pregnant women who experience gestosis, edema, elevated blood pressure, and excess weight are at risk due to hyperplasia of the "baby’s place" in its later stages.
The functions of the placenta are significantly impaired by thickening, especially the protective function. If hyperplasia is caused by an infection, such a placenta will not be able to protect the baby, it is highly likely to become infected and may die in utero. Early stages of thickening do not make themselves known in any way. Only by undergoing ultrasound diagnostics is it possible to determine such a violation. But in the later stages, the woman will be "informed" about the development of pathology by the baby"s movements: he will begin to show pronounced anxiety, and then episodes of motor activity will become less frequent. CTG can detect violations of the fetus"s condition, the uteroplacental blood flow on the ultrasound Doppler will also be impaired.
Only after identifying the precise cause of the anomaly is a course of action recommended. If the condition is an infection, the woman is prescribed antimicrobial or antiviral therapy; if the condition is diabetes mellitus, an endocrinologist prescribes a standard course of treatment; if the condition is gestosis, hospitalization may be necessary in addition to a diet and blood pressure normalization. Regretfully, there aren’t any drugs that could make the placenta thinner. It is advised to a woman to take medication to increase blood flow in the uteroplacental vessels. "Actovegin" and "Curantil" are most frequently used. Iron preparations, as well as vitamin and mineral supplements, are also prescribed.
An intrauterine blood transfusion may be done if there is a Rh conflict.
Thin
Underdevelopment or hypoplasia of the "baby’s place" is the term used to describe the situation when the placenta’s thickness for a given period of time does not surpass the values of the lower limit of the allowed range. The placenta in question exhibits restricted functionality, and its normalcy is contingent upon one specific circumstance: the expectant mother is of a small build and is in fragile physical condition. In this instance, the baby’s development won’t be hampered.
In all other situations, an undeveloped "baby’s place" can have detrimental effects, such as hypoxia, delayed development, and increased risk of infant death. Sometimes a thin placenta indicates genetic abnormalities in the developing fetus. There is an increased risk of placental thinning following early-stage viral infections and from sexually transmitted infections. One of the most common causes of hypoplasia in women is gestosis during the second half of pregnancy. Other common causes include chronic kidney, heart, and thyroid gland diseases. Thinning is frequently caused by alcohol and drug use, as well as smoking during pregnancy.
Hypoplasia typically results in a delay in the baby’s intrauterine development. The mother’s diet can be changed, vitamins taken, and medications that increase uteroplacental blood flow can all help to solve the issue. It is impossible to eradicate IUGR if the underlying causes are chromosomal abnormalities or developmental defects in the fetus.
| Weeks of Pregnancy | Placenta Thickness |
| 8-12 weeks | 2-4 mm |
| 13-16 weeks | 4-6 mm |
| 17-20 weeks | 6-8 mm |
| 21-24 weeks | 8-10 mm |
| 25-28 weeks | 10-12 mm |
| 29-32 weeks | 12-14 mm |
| 33-36 weeks | 14-16 mm |
| 37-40 weeks | 16-18 mm |
Knowing the placenta’s thickness during pregnancy is crucial for keeping an eye on the mother’s and the unborn child’s health. Frequent examinations can help guarantee that the placenta is growing normally and giving the developing child the vital nutrients and oxygen it needs.
Healthcare professionals can identify potential problems early on, such as placental insufficiency or other complications, by monitoring the placenta’s normal growth patterns. Supporting a healthy pregnancy is greatly aided by this proactive approach.
Never stop talking to your doctor, and don’t be afraid to ask any questions you may have regarding your placenta or any other concerns. You can feel more connected to the process and have peace of mind if you are knowledgeable and involved in your pregnancy.
