Morning sickness is a term to describe the feeling of discomfort experienced by pregnant women who are in the first trimester of pregnancy. Malaise is best defined as food aversions, nausea, and vomiting. It is called "morning sickness" because many women experience it as soon as they get up (Profet, 1995); but in reality morning sickness could occur at any time of the day. So the term morning sickness may be a misnomer. There are several other terms used including nausea and vomiting in pregnancy (NVP) rather than morning sickness (Flaxman & Sherman, 2000). The term NVP will be used throughout this essay. Generally, each of us has a tolerance threshold to toxins to detect the level of toxicity in the blood; and if this threshold is exceeded, it will induce nausea and vomiting. Similarly, NVP occurs when the normal tolerance threshold to the toxin is lowered; thus increasing the sensitivity in detecting toxin levels in the maternal blood to protect the embryo (Profet, 1995). There has been much speculation about the main causes of NVP and the benefits it brings to both the mother and the embryo. Many studies claim that NVP works to avoid toxic substances, although the depth of this claim has yet to be proven. In this essay I will review studies on NVP; and discuss whether NVP is an evolutionary act to protect the embryo. Symptoms of NVP peak during embryonic organogenesis (weeks 6–18) because this is the time when the embryo is most susceptible to chemical destruction (Flaxman & Sherman, 2000). Organogenesis is the period of formation of organs from the tissue layers ectoderm, mesoderm and endoderm. Physically expelling intolerable foods and feeling nausea are obvious signs of NVP. Commonly known as a short-term illness designed for long-term benefit, NVP begins… halfway through the document…) Foodborne infections during pregnancy. Food Protection Journal®. 62(7), 818-829.Tierson, FD, Olsen, CL & Hook, EB (1986) Nausea and vomiting of pregnancy and association with pregnancy outcome. American Journal of Obstetrics and Gynecology. 155 (5), 1017-1022.Trivers, R.L. (1974) Parent-child conflict. American zoologist. 14(1), 249-264.Watkins, A.J., Ursell, E., Panton, R., Papenbrock, T., Hollis, L., Cunningham, C., Wilkins, A., Perry, V.H., Sheth, B ., Kwong, WY, Eckert, JJ, Wild, AE, Hanson, MA, Osmond, C. & Fleming, TP (2008) Adaptive responses of early mouse embryos to maternal diet protect fetal growth but predispose to early-onset disease in adulthood. Reproductive biology. 78 (2), 299-306.Weathersbee, PS, Olsen, LK & Lodge, JR (1977) Caffeine and pregnancy. A retrospective investigation. Postgraduate medicine. 62 (3), 64-69.