There is a surprising degree of overlapping structure evident across the languages of the world. One factor leading to cross-linguistic similarities may be constraints on human learning abilities. Linguistic structures that are easier for infants to learn should predominate in human languages. If correct, then (a) human infants should more readily acquire structures that are consistent with the form of natural language, whereas (b) non-human primates' patterns of learning should be less tightly linked to the structure of human languages. Prior experiments have not directly compared laboratory-based learning of grammatical structures by human infants and non-human primates, especially under comparable testing conditions and with similar materials. Five experiments with 12-month-old human infants and adult cotton-top tamarin monkeys addressed these predictions, employing comparable methods (familiarization-discrimination) and materials. Infants rapidly acquired complex grammatical structures by using statistically predictive patterns, failing to learn structures that lacked such patterns. In contrast, the tamarins only exploited predictive patterns when learning relatively simple grammatical structures. Infant learning abilities may serve both to facilitate natural language acquisition and to impose constraints on the structure of human languages.

There is a strong inverse relationship between mGSD - CRL and first-trimester pregnancy loss in IVF patients, although the incidence of pregnancy loss with a mGSD - CRL <5 mm was significantly lower than previously reported. Small mGSD - CRL was not associated with an increased risk of complications in pregnancies that continued beyond 20 weeks. The association between mGSD, CRL, and miscarriage is complex.

Gestational surrogacy is an important fertility treatment that particularly benefits women with medical conditions that make pregnancy unsafe or impossible, men in same-sex couples, and single men. Though many countries and several states within the United States have laws against gestational surrogacy, most U.S. states allow the practice with few regulations. In this issue, Perkins et al. (1) document the resulting trends in increasing use and improving outcomes in the United States.In the past 15 years, the number of gestational carrier (GC) cycles increased by more than 470%, and a large majority (69.4%) of clinics now offer this treatment. The pregnancy outcomes are encouraging, as GC cycles using either donor or intended parent (nondonor) oocytes had higher implantation, clinical pregnancy, and live-birth rates compared with treatment cycles in which the intended parent carried the pregnancy. Another trend is an increase in cross-border reproductive care, or ''medical tourism,'' involving gestational surrogacy, with 18.5% of GC cycles performed for non-U.S.resident intended parent(s) (1).Although we are heartened to see improvements both in access to this important treatment and in the resulting pregnancy rates, the higher multiple-birth rates described by the authors is cause for concern. It is clear that a significant number of GCs and the resulting children are being exposed to the increased risks associated with multiple-gestation pregnancies.With the privilege of providing gestational carrier treatment comes the professional responsibility to practice safely and ethically: mitigating risks for the gestational carrier and the children born from gestational surrogacy and, in turn, the risks to our professional autonomy. Arguments in favor of surrogacy include the right to procreative liberty, privacy, and autonomy. Gestational surrogacy gives hope to individuals or couples who could not otherwise build a family outside of adoption. Arguments against gestational surrogacy include the commodification of women for reproduction, undue inducement related to compensation, and concerns about the best interests of the resulting child. Unlike traditional in vitro fertilization (IVF) cycles where the intended parent(s) take on any risks associated with the treatment, subsequent pregnancy, and delivery, gestational carriers are taking on many medical risks for a third party. The extreme variation in laws and practices between countries and even within the United States demonstrates the myriad legal and ethical complexities inherent in these arrangements (2).The Ethics Committee of the American Society for Reproductive Medicine (ASRM) recognizes the unique need to protect the interests of the GC through psychological counseling, independent legal counsel, and full informed consent regarding the risks of the gestational surrogacy process. As the committee opinion states, ''Special consideration should be given to transferring a single embryo in an effort to limit the risks of multiple pregnancy for the carrier.'' Howe...

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