A maternal bond is the relationship between a mother and her child. While typically associated with pregnancy and childbirth, a maternal bond may also develop in cases where the child is unrelated, such as an adoption. A maternal bond is the relationship between a mother and her child. While typically associated with pregnancy and childbirth, a maternal bond may also develop in cases where the child is unrelated, such as an adoption. Both physical and emotional factors influence the mother-child bonding process. In separation anxiety disorder a child becomes fearful and nervous when away from a loved one, usually a parent or other caregiver. New mothers do not always experience instant love toward their child. Instead, the bond can strengthen over time. Bonds can take hours, days, weeks, or months to develop. The maternal bond between a woman and her biological child usually begins to develop during pregnancy. The pregnant female adapts her lifestyle to suit the needs of the developing infant. At around 18 to 25 weeks, the mother begins to feel the fetus moving. Similar to seeing her child for the first time in an ultrasound scan, this experience typically leads the mother to feel more attached to her child. The developing fetus has some awareness of the mother's heartbeat and voice and has the ability to respond to touch or movement. By the seventh month of pregnancy, two-thirds of women report a strong maternal bond with their unborn child. Mothers who did not want the pregnancy typically do not have a close relationship with the child. They are more likely to suffer from post-partum depression or other mental health problems and less likely to breast feed. Childbirth is an experience that can strengthen the mother and child bond. Factors such as a traumatic birth, the mother's childhood, medical stress, lack of support and the influence of a spouse or partner can weaken the bond. Emotional bonding theory first appeared in the mid-1970s, and by the 1980s had become an accepted phenomenon. Soon, the process became analyzed and scrutinized to the point of creating another term – poor bonding. Production of oxytocin during childbirth and lactation increases parasympathetic activity. Thus, anxiety is theoretically reduced. Maternal oxytocin circulation is said to predispose women to bond and show bonding behavior, although this has been disputed. Breastfeeding is also strongly believed to foster the bond, via touch, response and mutual gazing.