Effects of social stress during early pregnancy on litter size and sex ratio in the golden hamster (Mesocricetus auratus)

Abstract

Primiparous female hamsters were mated to proven breeders and stressed during early pregnancy. Females were housed singly throughout gestation except for Days 4, 5 and 6 when they were paired for 10-min intervals 3 times each day with another female matched for age, weight and day of pregnancy. Within each of the pairs, one female was consistently dominant to the other. Controls were exposed to a novel area instead of a conspecific. At parturition, all pups were counted, sexed and weighed. There were no significant differences between litter sizes or sex ratios (defined as % male) of control and dominant females. Litter sizes produced by control or dominant dams were significantly larger than those of subordinate dams, and litter sex ratios of dominants were significantly higher than those of subordinates. Subordinate dams produced fewer males than did dominant dams, but there was no difference in the number of females produced. Also, subordinate dams produced smaller pups than control dams. Examination of uterine implantation sites and fetal resorptions indicated that fetal loss occurred between Days 5 and 10 of pregnancy. These results suggest that subordinate dams produce smaller litters via selective resorption or spontaneous abortion of males in utero and that those males they do produce are smaller than those produced by dominant or control dams. We suggest that males are more susceptible in utero to effects of maternal stress in this species, and may require more maternal investment to survive to term.

Expression of adrenergic receptors in mouse preimplantation embryos and ovulated oocytes

“…Some results suggest that maternal stress can negatively impact on the embryo even at very early stages of its development. For instance, it has been shown that litter sizes of female hamsters stressed during early pregnancy were significantly smaller than those of controls, with fetal loss occurring between days 5 and 10 of pregnancy (Pratt & Lisk 1989). In humans, it has been demonstrated that pregnancies characterized by increased maternal cortizol (commonly used stress marker) during the first three weeks after conception are more likely to result in spontaneous abortion.…”

Leptin Resistance as a Cause of Lack of Eating Behavior Changes in Hyperleptinemia and Obesity in Female Rats — Offspring of Gestational Stressed Mothers

“…Методика вiдтворення вказаного типу стре-су пiд час гестацiї та отримання нащадкiв описано в роботi N. C. Pratt, R. D. Lisk [15]. Умови утримання всiх нащадкiв вiд наро-дження до 11-мiсячного вiку були iдентични-ми та вiдповiдали рекомендацiям по утри-манню щурiв [16].…”

Subjecting Holstein Heifers to Stress During the Follicular Phase Following Superovulatory Treatment May Increase the Female Sex Ratio of Embryos

“…Dev. 55: [529][530][531][532][533]2009) he sex ratio of mammals (humans, rodents and ruminant ungulates) has been shown to be affected by many factors, such as nutrition, season, disease, levels of gonadotrophin and steroid hormones, social status, stress, age and parity [1][2][3][4][5]. In the 1970s, Trivers and Willard [6] hypothesized that the physical condition of the individual female during the periods of maternal investment influences the sex ratio of progeny.…”

“…Stresses can be acute (short term), such as earthquakes, floods or sudden bereavement, or chronic (long term), such as food shortages, wars or epidemics. In rodents, females stressed acutely in some manner tend to produce fewer sons than non-stressed females [2,3,7]. The concentration of cortisol or corticosterone in plasma is used to assess stress [8].…”