Premature birth and low birthweight are associated with a lower rate of reproduction in adulthood: a Swedish population-based registry study.

BACKGROUND: The aim of this study was to investigate if individuals born with sub-optimal birth characteristics have reduced probability of reproducing in adulthood. METHODS: Using population-based registries, the authors included 522 216 males and 494 692 females born between 1973 and 1983 and examined their reproductive status as of 2006. Outcome measure was the hazard ratio (HR) of reproducing. Adjustments were made for socio-economic factors. RESULTS: Males and females born very premature displayed a reduced probability of reproducing [HR = 0.78, 95% confidence interval (CI): 0.70-0.86 for males; HR = 0.81, CI: 0.75-0.88 for females]. Likewise for very low birthweight (HR = 0.83, CI: 0.71-0.95 for males; HR = 0.80, 95% CI: 0.72-0.89 for females). Individuals born large for gestational age (LGA) displayed no significant changes. Males born small for gestational age (SGA) had a 9% lower reproductive rate (CI: 0.89-0.94) and that reduction increased as the individuals aged. Women born SGA tended to start reproducing at an earlier age. CONCLUSION: The results suggest that being born with low birthweight, premature or SGA (for males) is associated with a reduced probability of reproducing as an adult. LGA shows no statistically significant relationship with future reproduction.

Role of dietary iron in maturation of rat small intestine at weaning.

The weanling process is characterized by the transition from a liquid diet poor in iron (rat milk) to a solid diet high in iron (chow pellets). To examine the effects of iron content of the weanling diet on terminal maturation of rat small intestine, suckling pups, nursed by iron-sufficient mothers, were weaned by day 16 onto a solid basal diet that was either deficient [low-iron diet (LID): 0.5 mg iron/100 g solid] or high [high-iron diet (HID) controls: 30 mg iron/100 g solid] in iron. The animals were studied during or at the end of the 4th postnatal wk. By day 17 rats weaned onto the LID exhibited an initial rise in jejunal sucrase activity as did their controls, but the activity plateau of the enzyme was reduced to a level 60% of the controls. On day 28 iron-deprived rats were anemic and showed significant decreases (P less than 0.01 compared with HID rats) in the activity of jejunal sucrase (-57%), neutral lactase (-83%), and maltase (-46%), whereas villus height, crypt depth, mucosal mass parameters, ileal acid beta-galactosidase activity, mucosal protein, and DNA synthesis rates were equivalent in LID and HID groups. The concentration of the secretory component, a glycoprotein synthesized by the intestinal crypt cell, was markedly depressed (P less than 0.01 vs. controls) in the jejunum (-54%) and ileum (-79%) of iron-deprived rats. When D-[1-14C]glucosamine was injected intraperitoneally, incorporation of the label into jejunal and ileal brush-border proteins was two to three times lower for iron-deficient rats than for controls.(ABSTRACT TRUNCATED AT 250 WORDS)