Placenta accreta spectrum is a condition in which the placenta abnormally attaches to the uterine wall (muscle) during the pregnancy. At the outset of a normal pregnancy, the placenta forms from cell division of the zygote (the initial fertilized eg). Part of these dividing cells nestle into the uterine lining covering the wall of the uterus and grow into the placenta, while the other part of the diving cells develop to become the embryo (and later fetus), which is connected to the placenta through the umbilical cord. The uterine lining (endometrium) is a mucosal layer of cells that is produced by the body specifically for the purpose of allowing the placenta to implant and grow drug pregnancy. If the endometrium does not grow properly, for instance because it was damaged due to previous uterine surgery such as a prior cesarean section or an endometrial ablation, the placenta will sometimes attached directly to the underlaying uterine wall instead. Therefore, placenta accreta is considered to be a spectrum, based on the degree of ingrowth of the placenta into the uterine muscle. If the placenta is merely attached to, but not necessarily grown into, the uterine wall, the condition is considered a classical placenta accreta. If the placenta has actually grown into the uterine wall, the condition is considered a placenta increta. If the placenta has grown through the uterine wall and invaded other structures and organs, such as the bladder, the condition is considered to be a placenta percreta. The prevalence of placenta accreta spectrum is relatively low, although it has risen considerably in recent years, likely due to the increased use of uterine surgeries and procedures since the 1970s and 1980s. Now, it is estimated that between 0.2 % and 0.4 % of pregnancies (2 to 4 out of 1,000) are affected by placenta accreta spectrum. Placenta accreta spectrum often does not present with any symptoms and can even remain undetected on ultrasound exams. If therefore, placenta accreta is not diagnosed prior to the delivery, it can cause serious complications during the delivery, including hemorrhages and birth injuries. This is why it is important to be aware of the potential risk factors discussed below and, if necessary, discuss careful monitoring and possible treatment approaches with your doctor.