The tiny being growing slowly and steadily inside a pregnant woman should be monitored regularly to ensure that it is growing and developing appropriately. There is nothing that can assure a mother of the health of her baby but through a series of assessments and tests that she herself would participate in. While the baby is still inside the womb, assessment of her well-being must already begin.
Estimating Fetal Growth
- McDonald’s rule is the measurement of the fundal height from the symphysis pubis.
- To measure, instruct the woman to lie supine and start measuring from the symphysis pubis to the uterine fundus.
- The distance between in centimeters depicts the week of gestation between the 20th to the 31st weeks of pregnancy.
- At 12 weeks, the uterine fundus should be at the level of the symphysis pubis.
- At 20 weeks, the uterine fundus should be at the level of the umbilicus.
- At 36 weeks, the uterine fundus should be at the level of the xiphoid process.
- Quickening or the first fetal movement that is felt by the mother usually starts at 18 to 20 weeks of pregnancy.
- A healthy fetus moves at an average of at least 10 times a day.
- In the Sandovsky method, to assess the fetal movement, ask the woman to lie in a recumbent position after a meal and record the number of fetal movements within an hour.
- In every 10 minutes, the fetus normally moves at least twice or 10 to 12 times in an hour.
- If there is less than 10 movements in an hour, the woman should repeat the procedure for the next hour.
- The Cardiff method or the “Count-to-Ten” method, the woman records the time interval between every 10 fetal movements she feels within 60 minutes.
Fetal Heart Rate
Rhythm Strip Testing
- The normal fetal heart rate is 120 to 160 beats per minute.
- In rhythm strip testing, the fetal heart rate is assessed if a good baseline heart rate or a degree of variability is present.
- The results are categorized as absent (none apparent), minimal (extremely small fluctuations), moderate (a range of 6-25 beats per minute), and marked (range over 25 beats per minute).
- The rhythm strip testing is done as the woman is asked to remain in a fixed position for 20 minutes.
- In a nonstress testing, the response of the fetal heart rate is measured in response to the fetal movement.
- The woman is attached to a fetal heart rate and uterine contraction monitor.
- The woman should push the button of the monitor whenever she feels the fetus move.
- Normally, when the fetus moves, the fetal heart should increase for about 15 beats per minute and remain elevated for 15 seconds.
- The nonstress test is done for 10 to 20 minutes.
- The result is reactive if there are two accelerations of fetal heart rate lasting for 15 seconds that occurs after movement.
- The result is non reactive if there are no fetal accelerations after a fetal movement, or there is no fetal movement.
- If the nonstress test is nonreactive, a contraction stress test or biophysical profile will be scheduled.
Contraction Stress Testing
- In contraction stress testing, the fetal heart rate is assessed in conjunction with uterine contractions.
- The woman is attached to an external uterine contraction and fetal heart rate monitor.
- The woman is instructed to roll a nipple between her fingers and thumb to produce uterine contractions.
- Within a 10-minute window, three contractions with a duration of 40 seconds or longer must be present.
- The test is negative or normal if there are no decelerations in the fetal heart rate during contractions.
- It is positive or abnormal if there is a late deceleration at the end of a contraction and even after the contraction.
- Ultrasonography measures the response of sound waves against solid objects.
- It can diagnose a pregnancy of 6 weeks’ gestation, confirm the presence, size, and location of the placenta, establish that the fetus is growing, detect any gross anomalies, establish the fetal sex, and determine the presentation and position of the fetus.
- The woman has to have a full bladder at the time of the procedure.
- Have the woman drink a full glass of water every 15 minutes 90 minutes before the procedure until the start of the procedure.
- Ultrasonography is also used to predict fetal maturity by the measurement of the biparietal diameter of the fetal head.
- Placental grading can also be done through ultrasound as 0 (12 to 24 weeks), 1 (30 to 32 weeks), 2 (36 weeks), and 3 (38 weeks).
- The amount of amniotic fluid present can also be detected through ultrasonography and is also a way to estimate fetal health.
- As early as the 11th week of pregnancy, fetal ECG can be recorded.
- However, fetal ECG is inaccurate before the 20th week as the fetal electrical conduction is still weak.
Magnetic Resonance Imaging
- MRI does not have any harmful effects to both the mother and the fetus, and is now largely considered as one of the preferred fetal assessment techniques.
- MRI can diagnose complications like ectopic pregnancy and trophoblastic disease or H-mole because fetal movements could hide the findings later in pregnancy.
Maternal Serum Alpha Fetoprotein
AFP is found in the amniotic fluid and the maternal serum and is produced by the fetal liver.
- MSAFP levels start to increase at 11 weeks’ gestation and increases steadily until term.
- The MSAFP level is abnormally high if there is a spina bifida defect or abdominal defect.
- The MSAFP level is low if the fetus has a chromosomal defect such as Down syndrome.
- The MSAFP is assessed at the 15th week of pregnancy and can detect 85% to 90% of neural tube defects and 80% of Down syndrome.
Amniocentesis is the aspiration of amniotic fluid from the pregnant uterus for examination.
- The test is typically done between the 14th and 16th weeks of pregnancy so that there is a generous amount of amniotic fluid present.
- Before the procedure, instruct the woman to void, and then place her on a supine position.
- Fetal heart rate and uterine contraction monitors are attached to the woman, and blood pressure and fetal heart rate are taken.
- An ultrasound is performed first to determine the position of the fetus and the location of a pocket of amniotic fluid and the placenta.
- Antiseptic solution is applied to the abdomen and local anesthetic is injected.
- Inform the woman that she might feel pressure as the needle is introduced, but do not advise her to take a deep breath and hold it in.
- About 15 mL of amniotic fluid is aspirated.
- Amniotic fluid is analyzed for AFP, bilirubin determination, chromosome analysis, color, fetal fibronectin, inborn errors of metabolism, lecithin-sphingomyelin ratio, and phosphatidylglycerol and desaturated phosphatidylcholine.
- The biophysical profile combines five parameters into one assessment.
- Fetal heart rate and breathing measure short-term central nervous system function.
- The amniotic fluid volume measures long-term adequacy of placental function.
- The biophysical profile is more accurate than any other single assessment method.
- The score ranges from 2-10, with 10 as the highest.
- If the fetus has a score of 8 to 10, it is doing well.
- If the score is 6, this is considered suspicious.
- A score of 4 denotes that fetus might be in jeopardy.
- The assessment is similar to that of an Apgar scoring, and it is commonly called as fetal Apgar.
Fetal assessment is just one of the many assessments that a pregnant woman must undergo to ensure the health of the fetus and even her own health. Undergoing these tests can give comfort to the mother regarding the status of her baby’s health, and compliance of her health care provider’s orders is the key to a healthy and safe pregnancy.