Normal Singleton Pregnancy: Management, Necessary Examinations, Risk Factors

A normal pregnancy is a pregnancy with a single fetus without genetic abnormality that occurred through natural conception and is defined as physiologic.

The expected date of delivery is initially set by counting 280 days from the first day of the last menstrual period. However, this method has inaccuracies because only 50% of patients remember the date of their last menstrual period accurately and some patients have irregular menstrual cycles. Human chorionic gonadotropin (hCG) levels in the pregnant woman’s blood and ultrasound can be used to determine the gestational age.

A 3D Model of a singleton pregnancy:

Appearance of a pregnant woman in the third trimester of pregnancy

Anatomical position of organs in premature pregnancy

Uterus, fetus and fetal membranes

Fetus, umbilical cord, and placenta in the longitudinal head position of the fetus

Longitudinal position of the fetus

Examination methods for normal pregnancy

A list of laboratory tests should be ordered at the initial presentation of the patient and the diagnosis of pregnancy. Patients with risk factors may be offered additional laboratory tests.

General clinical examinations

• Blood type;
• Screening for anti-erythrocyte antibodies;
• General blood work;
• Urinalysis, urine culture.

Infection screening during pregnancy

• Gonorrhea;
• Chlamydia;
• Syphilis;
• Human Immunodeficiency Virus (HIV);
• Hepatitis B virus;
• Hepatitis C virus;
• Rubella;
• Chickenpox;
• Human papillomavirus (HPV) – if the patient has a history of abnormal cervical screening;
• Herpes simplex virus (HPV);
• Asymptomatic bacteriuria;
• Tuberculosis;
• Group B Streptococcus (GBS) is the leading cause of serious neonatal infections (e.g., sepsis, meningitis, pneumonia) during the first 7 days of life. Antenatal screening is recommended for all pregnant women between 36 0/7 and 37 6/7 weeks gestation.

In order to diagnose pathological conditions, a number of tests are additionally performed:

• Cervical cytologic examination with HPV DNA detection – cervical cancer screening;
• Preeclampsia risk assessment – a comprehensive metabolic panel;
• Risk assessment for pre-eclampsia is urine protein/creatinine ratio;
• Risk assessment of gestational diabetes mellitus – oral glucose tolerance test with 75 g glucose;
• Diagnosis of pregestational diabetes mellitus – checking hemoglobin A1C levels;
• Analyzing thyroid hormone levels – assessing the presence of thyroid disease.

First ultrasound scan (ultrasound)

Obligatorily performed in the first trimester to establish or confirm gestational age and estimated date of delivery, and to confirm the presence of a heartbeat.

Other indications for ultrasound are:

• Diagnosis of the causes of vaginal bleeding;
• Confirmation of the intrauterine location of the embryo;
• Presence and course of multiple pregnancies;
• Presence of uterine anomalies or the presence of other pelvic organ pathologies.

Patients with complaints of bleeding or pain when seeking care should be referred immediately for ultrasound.

Genetic screening

Testing for aneuploidy is a mandatory prenatal test regardless of risk factors and maternal age. Modern aneuploidy screening based on cell-free DNA is performed by looking for total cell-free DNA of the 21st, 18th, 13th and X chromosomes in the blood. This test can be performed from the 10th week of pregnancy onwards.

The assay determines the likelihood of a child having:

• Trisomy 21 is the presence of 3 copies of the 21st chromosome in all cells of the body. It is the most common cause of a genetic condition called Down syndrome.
• Trisomy 18 is the presence of 3 copies of the 18th chromosome in all cells of the body. This disorder is called Edwards syndrome.
• Trisomy 13 is the presence of 3 copies of the 13th chromosome in all cells of the body. This disorder is called Patau syndrome.
• X monosomy is the presence of only 1 copy of the X chromosome, called Turner syndrome.

It is worth saying that this test only determines the probability of aneuploidy, for a definite diagnosis it is necessary to perform a biopsy of chorionic villi or amniocentesis.

In addition to aneuploidy tests, the maternal serum alpha-fetoprotein concentration is determined. This test is used to screen for neural tube defects and is performed between 15 and 22 weeks of pregnancy. Importantly, this test is not part of first trimester screening.

It is also possible to have genetic testing before pregnancy without having to repeat it in the future. Genetic tests include diagnosis of hemoglobinopathy, cystic fibrosis carrier screening, and spinal muscular atrophy.

If there are cases of genetic anomalies in the patients’ relatives, such a group of patients is subject to extended genetic screening.

Risk factor assessment

At the initial exam, the doctor should assess the presence of certain risk factors in order to prevent the development of pregnancy complications.

1. Preeclampsia

Preeclampsia is a leading cause of maternal morbidity and mortality. Early evaluation may include a complete metabolic panel and urine protein/creatinine ratio testing in patients with underlying liver or kidney disease.

High-risk factors:

• A history of preeclampsia;
• Multiple pregnancies;
• Chronic arterial hypertension;
• Pregestational type 1 or type 2 diabetes mellitus;
• Kidney disease;
• Autoimmune disease (e.g., antiphospholipid syndrome, systemic lupus erythematosus).

Moderate risk factors:

• Obesity (body mass index > 30);
• Family history of preeclampsia;
• African people (due to social rather than biological factors);
• Low income;
• Age 35 and older;
• In vitro conception;
• Personal risk factors.

Patients with one or more high-risk factors or two or more moderate-risk factors should take low-dose aspirin with initiation of therapy between 12 and 28 weeks’ gestation (optimally up to 16 weeks’ gestation).

2. Diabetes mellitus

Gestational diabetes mellitus (GDM) develops in 4% of all pregnancies. Risk factors include:

• Presence of a previous pregnancy with the development of GDM;
• Being overweight or obese;
• Presence of a family history of DM;
• Patients are African American, Hispanic, American Indian, Alaska Native, Native Hawaiian, or Pacific Islander;
• Patients taking antiretroviral therapy.

Early screening for GDM is indicated in patients with multiple risk factors for GDM. Early screening is performed at 14-20 weeks, as opposed to the standard diagnosis at 24-28 weeks.

3. Preterm labor

Preterm labor develops in 1 in 10 cases and is the leading cause of perinatal morbidity and mortality.

Risk factors include:

• Previous preterm labor;
• Multiple pregnancies;
• Development of isthmic-cervical insufficiency.

4. Depression Screening

Patients are screened for depression at first presentation, at 28 weeks of pregnancy and in the postpartum period. Screening using the Edinburgh Postpartum Depression Scale (EPDS) is recommended. Patient Health Screening and the Patient Health Questionnaire (PHQ-9) are also used.

5. Substance use

The use of alcohol, cigarettes, cannabis, drugs or teratogenic medications is common and may be associated with the development of side effects.

6. Immunization assessment

All pregnant and breastfeeding women should be immunized according to their country’s vaccination calendar. Immunization reliably reduces the risk of disease during pregnancy. Pertussis and influenza vaccines are administered during each pregnancy.

7. Pelvic muscle function

In early pregnancy, a brief assessment of the pelvic floor muscles by palpation followed by instruction on appropriate muscle contraction without activation of compensatory patterns (e.g., activation of gluteal or adductor muscles) should be performed.

Regularity of monitoring during pregnancy

The frequency of visits is determined on an individual basis. Typically, a patient with an uncomplicated first pregnancy is seen every 4 weeks until 28 weeks of gestation, then every 2 weeks from 28-36 weeks of gestation, and then every week until delivery.

At each visit, the physician should assess blood and urine counts, blood pressure, weight, uterine fundal height to assess fetal growth progression, and the presence of cardiac activity and fetal movement at the appropriate gestational age.

Fetal ultrasound to assess fetal anatomy in the 2nd and 3rd trimesters

It is used to assess fetal growth and anatomy and to detect fetal anomalies. Ultrasound is recommended as an accurate method of detection:

• Gestational age;
• Number of fruits;
• Embryo viability;
• Anatomical examination;
• The location of the placenta;
• Volume of amniotic fluid;
• Pelvic organ assessments.

Optimal timing of fetal anatomy ultrasound:

• From 18 to 22 weeks of pregnancy in the second trimester;
• Weeks 32 through 35 in the third trimester.

Diagnosis of fetal malformations significantly reduces perinatal mortality and morbidity, as well as maternal morbidity. Prenatal diagnosis allows psychologically less traumatic and earlier medical termination of pregnancy in patients with medical indications for termination.

Management of labor in singleton pregnancies

The onset of labor is defined after 24 weeks of gestation as the presence of regular and painful uterine contractions resulting in dilation and flattening of the cervix.

The first stage of labor is defined as the interval between the onset of labor and the full or 10-centimeter opening of the cervix. The first stage is also divided into two phases:

• The latent phase of labor is characterized by a gradual and relatively slow dilation of the cervix, which begins with the onset of regular uterine contractions and ends when the cervix is completely flattened.
• The active phase continues until the full opening of the uterine yawn, which is the beginning of the second phase.

The second period of labor ends after the fetus is delivered.

The third period of labor is the period between the delivery of the newborn and the birth of the placenta.

Sequence of fetal movements during pelvic passage for an anterior occipital presentation

1. Lowering and flexion of the head: the head enters the pelvis in an occipitoposterior position with the chin pressed against the chest (flexion of the head).
2. Internal rotation to the occipitoposterior direction – occurs at the level of the sciatic ostia with the establishment of the arrow-shaped suture in the longitudinal direction and the fixation point under the bunion.
3. Flexion of the head occurs in the plane of the pelvic outlet.
4. External rotation: the shoulders rotate when they reach the levator muscles until the biacromial diameter is established in the anteroposterior direction.
5. Anterior shoulder birth: occurs by laterally bending the fetal body posteriorly.
6. Posterior shoulder birth: occurs by lateral flexion of the fetal body to the front, followed by the rest of the body.

In the case of posterior occipital presentation, the fetus requires additional flexion of the head after internal rotation of the head.

Management of the first period of labor

Observation in the first period of labor is recorded on a partogram:

• Careful collection of anamnesis and study of the history of the course of pregnancy.
• Palpation of the abdomen with determination of position and presentation, recording the frequency and duration of contractions every 30 minutes.
• Fetal assessment: heart rate and color/quantity of amniotic fluid. Measurements are taken every 30 minutes or continuously with CTG.
• Maternal assessment: heart rate is assessed every hour, blood pressure (BP) and temperature are measured every 4 hours. Urinalysis with determination of ketone bodies and protein is performed every 4 hours. Analgesia is performed as indicated.
• Assessment of vaginal status: cervical opening dynamics, fetal head position is performed every 4 hours or when the obstetric situation changes.
• Performing amniotomy as indicated with reassessment of the condition after 2 hours.

Management of the second period of labor

Labor should take place within 1 hour of active labor for non-pregnant women and within 40 minutes for repeat women. The fetus is monitored continuously by CTG. During this period, continuous clinical monitoring of the patient’s general condition is performed:

• Consciousness;
• Skin and mucous membrane color;
• Pulse and BP.

Women can choose a variety of positions for childbirth:

• Sitting;
• Standing on hands and feet or upright;
• Lying on your back.

When the head erupts, the perineum and anus are stretched. The midwife’s task at this stage is to prevent premature extension of the fetal head and to control the speed of labor. For this purpose, the midwife uses four fingers of one hand placed on the fetal head to provide a slight obstruction. Episiotomy or perineotomy is indicated if there is a risk of perineal rupture, but should not be used routinely.

The fetal head is released outside of labor, which reduces the risk of perineal rupture. If the shoulders are not self-bearing, the head should first be gently pulled downward, facilitating the birth of the anterior shoulder. Next, use the other hand to lift the fetal head anteriorly and then pull the perineum down from the posterior shoulder to prevent injury.

If this technique is ineffective, the assistance for shoulder dystocia is used. After birth, the umbilical cord is clamped and cut twice: a delay in clamping for 2-3 minutes leads to an increase in the level of hematocrit in the newborn. The baby’s condition is assessed at 1, 5 and 10 minutes on the Apgar scale.

If labor cannot be delivered within 1 hour of active labor, surgical termination of labor should be considered. Vacuum extraction or caesarean section may be performed.

Importantly, conditions must be met for vacuum extraction to take place:

1. A living fetus;
2. The cervix is fully dilated;
3. Absence of a fetal bladder;
4. Matching the size of the maternal pelvis and fetal head;
5. Location of the fetal head in a wide, narrow part of the pelvic cavity or outlet;
6. Occipital or anteroposterior insertion;
7. Active participation of the laboring woman;
8. Informed consent of the woman in labor.

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Management of the third period of labor

The third period of labor begins with the birth of the fetus and ends with the birth of the placenta, membranes and umbilical cord. Separation occurs due to less intense and painful contractions, and the uterus significantly decreases in size with the bottom near the navel and takes on a rounded shape.

Before pushing the patient, the midwife performs a control traction of the umbilical cord by supporting the uterine fundus with the left hand. The umbilical cord should come off and lengthen easily. If the birth of the placenta is difficult, techniques may be used to release the detached afterbirth.

The duration of the third period is on average up to 30 minutes, regardless of the parity of labor. If the placenta cannot be separated, manual separation of the placenta and separation of the afterbirth is performed. This operation is performed under anesthesia. With the help of a hand inserted into the uterine cavity, the doctor determines the edge of the placenta and then sawtooth movements separate the placenta from the uterine wall. Then the placenta is extracted by traction by the umbilical cord and a control examination of the uterine cavity is performed.

In physiologic labor, total blood loss does not exceed 250 ml or 0.5% of the woman’s weight. Blood loss in excess is pathologic and requires management tactics aimed at stopping the bleeding, depending on the cause.

The following causes of postpartum hemorrhage are distinguished:

• T (tonus) – a disorder of uterine contraction (atony);
• T (tissue) – placental tissue retention;
• T (trauma) – trauma to the birth canal;
• T (thrombin) – blood clotting disorders.

Regardless of the blood loss, after placenta abruption, it is imperative to perform an examination of the birth canal, inspect the integrity of the placenta and membranes, and measure the pulse and blood pressure. In case of bleeding, a vaginal examination and manual examination of the uterine cavity is carried out. Additionally, auscultation of the lungs is performed.

The main causes of late postpartum hemorrhage (after 24 hours):

• Placental tissue remnants;
• Uterine subinvolution;
• Postpartum infection;
• Hereditary defects in hemostasis.