Fill in the Blanks Pregnancy stagesOnline version Fill in the blanks with words from the pregnancy stages by Miguel Angel Preciado Lopez 1 embryo amniotic Pregnancy uterus sac blastocyst amniotic cord 40 fluid zygote Fertilization button placenta umbilical foetus belly is the time from fertilization to birth . The time from fertilization to birth usually last weeks . takes place in one of the fallopian tubes . A sperm cell fuses with an ovum to form a . Cells divide to form a ball called a . When the ball of cells reaches the it attaches itself to the wall of the uterus . In the uterus , the develops . When all the organs are formed , the form is called the . The foetus grows in the , which protects it . The amniotic sac is filled with . The foetus is attached to the mother by the . The is the remains of the umbilical cord . The provides nutrients and oxygen , and removes waste products .