*2.1.1.3 Monochorionic/monoamniotic*

The frequency of visits for these twins is mainly determined by the course of the pregnancy and the follow-up should be more frequent because of the fact that the possible complications occur at higher rates, including TTTS and umbilical cord compression [22–30].

#### *2.1.1.4 Dichorionic*

18 weeks detailed fetal development test.

22–24 weeks detailed fetal heart ultrasound.

Every 2 to 4 weeks from the 24th to the 32nd week and every week until the birth to assess intrauterine development pathology in a timely manner.

EFW A difference of less than 25% between the EFWs of the two fetuses is considered normal.

Regular testing for hypertension (preeclampsia) should be done to avoid intravenous medication. The early diagnosis of gestational diabetes mellitus is done with increased glucose curve (increased complications in multiple pregnancies).

During these visits, weight gain, blood pressure and changes in the cervix (ultrasound or vaginal examination) should be carefully recorded.

In addition to the amniotic fluid index (AFI), important Doppler ultrasound indicators are: Doppler flow rate tachycardia (UA), umbilical artery pulse index (UAPI), middle cerebral artery Doppler, venous duct (DV) [22–30].

#### **2.2 Complications of twin pregnancy**

#### *2.2.1 Maternal complications*

Maternal complications in multiple pregnancies occur at higher rates compared to single pregnancies.

#### *2.2.1.1 Hyperemesis*

Hyperemesis appears due to increased placental mass and increased β-HCG levels. It is increasing and is a previous complication.

#### *2.2.1.2 Preeclampsia*

Compared to a single pregnancy, when there is an increased chance of preeclampsia, it doubles and quadruples. Atypical preeclampsia without hypertension is also common, but with hepatic and renal disorders. The incidence rate is 8.1% in dichorionic embryos, 6% in monochromatic ones, while respectively it is only up to 5% in single pregnancies. If other aggravating factors coexist, such as advanced maternal age of first pregnancy and BMI ≥35 Kg/m2, then 75 mg aspirin is recommended.
