Dra. Ana Margarida Mourato

Gynecology and Obstetrics Service

Assessment of fetal well-being:
Strategies for monitoring fetal healt

HPA Magazine 23 // 2025

The assessment of foetal well-being is one of the pillars of modern obstetrics, crucial for ensuringa healthy pregnancy and minimizing perinatal risks. It is based on the analysis of clinical and biophysical indicators that reflect the health of the foetus and its ability to adapt to adverse conditions. Among the available techniques, the following stand out:
• Monitoring foetal movements;
• Cardiotocography (CTG);
• Foetal biophysical profile;
• Doppler velocimetry.
Each offers complementary perspectives for early identification of signs of foetal distress, which can compromise foetal vitality.

Risk Factors for Foetal Distress
The absence of foetal well-being is often manifested by signs suggestive of hypoxic acidosis due to inadequate maternal-foetal gas exchange. If not identified and treated in time, it can progress to multiorgan dysfunction or perinatal death. Although some studies demonstrate that not all cases of perinatal death can be prevented, early detection of changes in foetal well-being is essential for targeted, personalized monitoring and effective timely intervention to minimize the risks of perinatal morbidity and mortality.
Risk factors associated with foetal distress include:
• Maternal: extremes of age, primiparity, African ethnicity, previous caesarean section, history of miscarriage or foetal death, obesity, maternal diseases (diabetes, hypertension, pre-eclampsia, kidney disease, thyroid disease, among others), smoking, infections, pain or abdominal trauma, urinary, gastrointestinal, respiratory, or vascular symptoms;
• Maternal-Foetal Interface Factors: changes in placentation, placental insufficiency, premature detachment of the normally inserted placenta;
• Foetal: congenital malformations, foetal growth restriction, oligo or polyhydramnios, decreased foetal movements;
• Obstetrics: postnatal, threatened premature birth, premature rupture of membranes, non-reassuring CTG, stationary labour, intrapartum fever, and cervical circles;
• Socioeconomic: low income, domestic violence, and chemical dependency.

Foetal Movements: Simple and Essential Indicator
Foetal movements reflect the neuromuscular development and vitality of the foetus, perceived by the pregnant woman from 16 to 24 weeks, peaking around 32 weeks and remaining until the end of pregnancy. Each foetus has a unique pattern, described as "butterflies"," flutters, or kicks, which can vary throughout the pregnancy. Changes in the pattern of foetal movements may be the first sign of foetal compromise, requiring additional evaluation with cardiotocography and ultrasound.

Cardiotocography
Cardiotocography (CTG) evaluates foetal heart rate and uterine contractility, identifying patterns indicative of hypoxia or foetal distress. It is especially useful in the third trimester when the foetal autonomic nervous system is more developed. The main parameters evaluated include:
• Foetal heart rate baseline: normal between 110 and 160 beats per minute (bpm);
• Variability: normal between 10 and 25 bpm;
• Accelerations: indicative of foetal well-being;
• Decelerations: May indicate foetal distress;
• Foetal movements: must be present;
• Uterine contractility.
Changes such as foetal tachycardia (increased number of heartbeats) or bradycardia (decreased number of heartbeats), repetitive or prolonged late decelerations, decreased variability, or changes in the pattern of foetal movements may indicate foetal distress and the need for immediate medical intervention.

Biophysical Profile
The biophysical profile evaluates foetal variables such as heart rate and reactivity assessed on cardiotocography, respiratory and body movements, tone, and amniotic fluid volume. It is recommended from 32-34 weeks in high-risk pregnancies and can be brought forward in certain cases.

Doppler Velocimetry
Doppler velocimetry analyses uteroplacental and foetal blood flow. Cases of reverse flow in the umbilical artery or increased flow in the middle cerebral artery are warning signs of severe hypoxia, often associated with the need for early termination of pregnancy. A foetus under hypoxia or acute foetal distress presents centralization of foetal circulation, a compensatory mechanism characterized by increased peripheral resistance and increased central vasodilation, redistributing blood flow to essential organs (brain, heart, and adrenal glands) at the expense of non-essential organs (kidney and gastrointestinal tract), resulting in decreased amniotic fluid and increased intestinal echogenicity. Given the persistence of centralization of foetal circulation, venous changes may occur, such as pulsations in the umbilical vein and retrograde flow in the venous duct, indicative of a high risk of perinatal morbidity and mortality.

Conclusion
Providing clear and objective information to pregnant women is crucial to ensuring effective foetal monitoring.
The assessment of foetal well-being combines simple methods such as foetal movement surveillance and advanced technologies such as CTG and ultrasound. This integrated approach significantly improves perinatal outcomes. Education of pregnant women and access to specialized care are essential to ensure a safe pregnancy and favourable maternal and perinatal outcomes.

The HPA Group provides resources such as the 24-Hour Mom Line (289 830 040), which offers permanent support to pregnant women, promoting a humanized and accessible approach at all stages of pregnancy.

Referências/References
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