Orlebeke J F, Boomsma D I, Eriksson A W
Department of Physiological Psychology, Vrije Universiteit, Amsterdam, The Netherlands.
Eur J Obstet Gynecol Reprod Biol. 1993 Jul;50(2):87-93. doi: 10.1016/0028-2243(93)90170-h.
From 112 triplet sets, born in The Netherlands from the end of 1986 to the beginning of 1991 and registered in the Dutch Twin Register, several details such as birth weight, gestational age, zygosity, and etiology were assessed by questionnaire, which was filled out by the mother. For 33 triplet sets, zygosity was also assessed by blood typing. Maternal smoking during pregnancy was also noted. Results show a very strong increase in number of triplets caused by artificial fertility enhancing techniques and consequently a shift in the relative contribution of zygosity types to the total number of triplets. Birth weight is predominantly influenced by gestational age. Other effects on birth weight are controlled for possible confounding with gestational age. First born triplets weigh more than later born triplets; boys weigh more than girls; nearly 25% of all individual triplets weigh less than 1500 g, i.e. belong to the category very low birth weight (VLBW); regular maternal smoking produces a 14% birth weight reduction; ovulation induction seems to decrease the sex ratio, i.e. hormonal treatment with ovulation inducing substances increases the probability of female offspring.
对1986年底至1991年初在荷兰出生并登记在荷兰双胞胎登记处的112组三胞胎进行了研究。通过母亲填写的问卷，评估了出生体重、孕周、合子性和病因等若干细节。对33组三胞胎还通过血型鉴定评估了合子性。同时记录了孕期母亲吸烟情况。结果显示，人工生育增强技术导致三胞胎数量大幅增加，因此合子性类型对三胞胎总数的相对贡献发生了变化。出生体重主要受孕周影响。对出生体重的其他影响因素已针对与孕周可能存在的混杂因素进行了控制。头胎三胞胎比后出生的三胞胎体重更重；男孩比女孩体重更重；近25%的三胞胎个体体重低于1500克，即属于极低出生体重（VLBW）类别；母亲经常吸烟会使出生体重降低14%；促排卵似乎会降低性别比，即用促排卵物质进行激素治疗会增加生出雌性后代的概率。
