The male to female ratio of newborn infants in Japan in relation to climate change, earthquakes, fetal deaths, and singleton male and female birth weights.

We have updated our work regarding climate extremes in Japan and the consequences of the huge earthquake in the Fukushima Prefecture in year 2011. We have interchangeably used the term sex ratio at birth, sex ratio of births. This ratio describes the secondary sex ratio, whereas the primary sex ratio designates the male/female ratio at fertilization.

Effects of earthquakes and other natural catastrophic events on the sex ratio of newborn infants.

Stress due to earthquakes and other natural catastrophic events may result in a decline in the male to female ratio of newborn infants. One reason may be an increased death of male fetuses 3-5 months earlier. Another reason may relate to reduced conception of males and/or early male embryo demise 8-10 months earlier.

Ultrasound Assessment of Lower Uterine Segment Thickness During Pregnancy, Labour, and the Postpartum Period.

Objectives: To evaluate the normal ranges of lower uterine segment (LUS) thickness throughout pregnancy in women without a previous cesarean and to evaluate the relationship between ultrasound and intraoperative LUS thickness.

Methods: We assessed LUS thickness using transabdominal and transperineal longitudinal scan at each week of gestation, during labour, and in the postpartum period in 1000 pregnant women without previous CS. Secondly, we assessed LUS thickness immediately before CS (using ultrasound) and intraoperatively (using ophthalmic calipers) immediately before delivery of the fetus in 35 women with a previous CS and 29 women without previous CS undergoing elective CS before labour.

Climate change is associated with male:female ratios of fetal deaths and newborn infants in Japan.

Objective: To evaluate whether climate change is associated with male:female ratios (sex ratios) of fetal deaths and births in Japan.

Design: A population-based cohort study.

Setting: Not applicable.

Paternal smoking habits affect the reproductive life span of daughters.

The present study assessed whether the smoking habits of fathers around the time of conception affected the period in which daughters experienced menstrual cycles (i.e., the reproductive life span).

The sex ratio of offspring is associated with the mothers' age at menarche.

Background: Early menarcheal age is a risk factor for breast and ovarian cancers and is also associated with an increased spontaneous abortion rate. The aim of this study was to investigate whether there is a link between early menarcheal age and the offspring sex ratio.

Methods: We recorded the sex of 21208 live born infants, all singletons, born to 10 847 premenopausal women (mean attending age: 37.

The ovulation pattern during three consecutive menstrual cycles has a significant impact on pregnancy rate and sex of the offspring.

Identification of the ovary at the time of ovulation during three consecutive menstrual cycles results in one of eight ovulation patterns, left-left-right, right-left-right, left-right-right, and right-right-right of right-sided ovulation and right-right-left, left-right-left, right-left-left, and left-left-left of left-sided ovulation. Our data suggest that IVF and IUI treatment in cycles in which development of the preovulatory follicle(s) occurs in the right-sided ovary-and ovulations took place from the left-sided ovary in the preceding two cycles (left-left-right)-is likely to show the best pregnancy potential and high offspring sex ratio.

Ovulation jumping from the left to the right ovary in two successive cycles may increase the chances of pregnancy during intrauterine insemination and/or in vitro fertilization natural cycles.

Identification of the ovary from which ovulation takes place in two consecutive menstrual cycles results in one of four ovulation patterns, contralateral and ipsilateral ovulations on the right or on the left ovary. Our data suggest that IVF and IUI treatment in cycles in which development of the dominant follicle occurs in the right-sided ovary--and ovulation took place from the left-sided ovary in the preceding cycle (contralateral right-sided ovulation)--is likely to show the best pregnancy outcome.

Do basal oestradiol and oestradiol:androgens and oestradiol:FSH ratios reflect pregnancy potential of women receiving intrauterine insemination during natural cycles?

The aim of this retrospective study was to evaluate whether basal hormone profiles could be related to the ability to achieve pregnancy in women receiving intrauterine insemination (IUI) treatment during their natural menstrual cycle. Serum hormone profiles on cycle day 3 of naturally menstruating women were assessed in a total of 163 treatment cycles (29 conceptional and 53 non-conceptional cycles of 27 women who became pregnant and 81 non-conceptional cycles of 33 women who did not become pregnant). Basal concentrations of LH, FSH and prolactin were similar between conceptional and non-conceptional cycles.

Parental periconceptional smoking and male: female ratio of newborn infants.

We assessed whether the smoking habits of parents around the time of conception affects the likelihood of the offspring being male or female. We found that the offspring sex ratio (male to female) was lower when either one or both of the parents smoked more than 20 cigarettes per day compared with couples in which neither of the parents smoked. We found the lowest sex ratio among children whose mothers and fathers both smoked more than 20 cigarettes per day (p<0.