Final answer:
The normal fetal heart rate pattern ranges between 110 and 160 beats per minute with a regular rhythm. Fetal viability is typically possible after 26 weeks of gestation with the fetal circulation and hemoglobin being specialized for intrauterine life. IUGR can cause low birth weight, while the average weight of a full-term infant is about 3.4 kg (7.5 lb).
Step-by-step explanation:
The analysis of Fetal Heart Tonic (FHT) patterns is an important part of monitoring the wellbeing of a fetus during pregnancy. The normal fetal heart rate pattern is typically between 110 and 160 beats per minute and will have a regular rhythm. Other patterns include:
- Sinusoidal rhythm: A smooth, wave-like pattern, which could be an indication of fetal anemia or hypoxia.
- Late deceleration: Gradual reductions in heart rate that occur after a contraction, possibly indicating uteroplacental insufficiency.
- Variable deceleration: Abrupt decreases in heart rate that can indicate cord compression.
- Early deceleration: Decreases in heart rate that occur at the same time as contractions, often benign and associated with head compression.
Fetal viability refers to the ability of the fetus to survive outside the womb, which is generally possible after 26 weeks of gestation. In terms of fetal development, a regular heartbeat can often be detected at around 6 weeks. The fetal circulation system is different from postnatal circulation due to the lungs not being in use. Fetal hemoglobin has a higher affinity for oxygen compared to adult hemoglobin, facilitating oxygen transfer from the mother to the fetus.
Regarding fetal growth, the size of the fetus generally increases linearly up until the week or two before birth. Intrauterine Growth Restriction (IUGR), often caused by placental insufficiency, may lead to low birth weight, which is a weight below 2.5 kg (5.5 lb). The average weight of a full-term infant is approximately 3.4 kg (7.5 lb).