Pregnancy at week 13, Now the fetus is the size of a lemon. The baby is constantly growing. Now, they are more than 2.5 inches (6.4 centimeters )long and weigh about 2.6 ounces (73 grams ). Five weeks ago, the fetus was the size of a kidney bean.
Their body is growing significantly, and this means that the head will soon be more proportionate to the rest of the body. The eyes are moving into position. The wrists and ankles are already well-formed.
By this stage in the pregnancy(Pregnancy at week 13), the ovaries or testes are fully developing internally, and the external genitalia is forming.
What will soon become the penis or clitoris is now developing rapidly. At this point, a health care provider might be able to determine the sex of the fetus on an ultrasound, but they might not be 100 percent sure.
The kidneys, ureters (tubes from the kidney to the bladder ), and bladder are forming at this point. The fetus is making a small amount of urine, which goes into the amniotic fluid to be recycled. Later on, in pregnancy, the baby will also breathe in this fluid to help expand and grow their lungs.
The fetus is now also making white blood cells to fights infection and red blood cells to carry oxygen around their body.