The aim of this study is to assess the feasibility of visualizing the internal thoracic artery (ITA), establishing the normogram for ITA pulsatility index (PI), resistance index (RI) and acceleration/ejection time (AT/ET) at 24-32 weeks.

Background: The internal thoracic artery arises from the subclavian artery as the first branch. It travels downward on the inside of the rib cage and then gives off six main branches; mediastinal, thymic, pericardiacophrenic, sternal, perforating and intercostal branches.

In literature, there are so many articles that have been focused on thymus size in pregnancies complicated with diabetes mellitus, fetal growth restriction, preterm rupture of membranes and so on. To the best of our knowledge, there is no paper about fetal ITA whose branch are feeding vessel of thymus and ITA Doppler velocity. The arteries supplying the thymus are branches of the internal thoracic, and inferior thyroid arteries. As far as it has been known, growing of a tissue depends on increased blood flow. Before detecting possible blood-flow changes in fetuses complicated with great obstetrics patologies, the investigators should obtain normal values of ITA Doppler velocity.

Inclusion Criteria:

• singleton pregnancy
• having no fetal anomalies
• healthy pregnant women age >17 and <45 years
• between 24th-32nd gestational weeks

Exclusion Criteria:

• fetuses with congenital aneuploidy or structural malformation
• underlying chronic diseases
• pregnant women complicated with gestational diabetes, Type 1-2 DM, hypertension (pregnancy-induced; chronic; preeclampsia), malignancy
• pregnancy complicated with preterm premature rupture of membranes, preterm labour, fetal growth restriction and another obstetric complication

Pregnant

healthy fetuses between 24th and 32nd gestational weeks