The success of pregnancy and vaginal delivery is highly dependent on the complex interaction between the uterine body, cervix, and fetal membrane [1]. Usually, this interaction is synchronized, following a specific sequence in normal vaginal deliveries: (1) cervical ripening, (2) decidual activation/rupture of fetal membrane, and (3) uterine contractions [2]. Serious complications during vaginal delivery may occur when this sequence is not followed, such as difficult labor progression [2]. Understanding the phenomena occurring during the late stages of pregnancy is essential to offer clinical guidance and solve these problems. This work analyzes the complex interaction between the cervix, fetal membrane, and uterine contractions before the onset of labor using a complete third-trimester gravid model of the uterus, cervix, fetal membrane, and abdomen. Through a series of numerical simulations, we investigate the impact of (i) initial cervical shape, (ii) cervical stiffness, (iii) cervical contractions, and (iv) intrauterine pressure on the resultant cervical shape and fetal membrane stress during uterine contractions. The findings reveal several key observations: (i) maximum principal stress values in the cervix decrease in more dilated, shorter, and softer cervices; (ii) reduced cervical stiffness produces increased cervical dilation, larger cervical opening, and decreased cervical length; (iii) the initial cervical shape impacts final cervical dimensions; (iv) cervical contractions increase the maximum principal stress values and change the stress distributions; (v) cervical contractions potentiate cervical shortening and dilation; (vi) larger intrauterine pressure (IUP) causes considerably larger stress values and cervical opening, larger dilation, and smaller cervical length; (vii) the biaxial strength of the fetal membrane is only surpassed in the cases of the (1) shortest and most dilated initial cervical geometry and (2) larger IUP. This is the first numerical study embracing a complete full gravid uterine and cervical model, uterine and cervical contractions, and a diversity of features associated with pregnancy. We hope to gain more insight into what conditions may influence a successful vaginal delivery and clarify the complex interaction between the cervix, fetal membrane, and body of the uterus, which is not entirely understood.