#5 – Morning Sickness May Be Worse
According to a study  of over 9,000 women in the UK, morning sickness may be more severe in the presence of a female fetus.
The reason for this may be that female fetuses do show a higher estrogen concentration.
And, the HCG (human chorionic gonadotropin), also called the “pregnancy hormone,” is higher for female fetuses compared to males, and remains higher during pregnancy.
#4 – Greater Chances Your Baby Will Come Later In Your Term
Studies show that it’s quite common for baby girls to be born later baby boys.
It’s important to note that being overdue is generally associated with fewer risks for the pregnant woman
According to a 2011 study conducted by the London School of Hygiene & Tropical Medicine, boys accounted for about 55% percent of preterm births.
And, it’s a pattern that happens all over the world. Scientists are not yet sure the reason behind this.
#3 – Girls Tend To Have Lighter Birth Weights
At birth, the average boy weighs 7 pounds, 10 ounces. Newborn girls have an average weight of seven 7 pounds, 2 ounces.
Girls also tend to be a shorter in length than boys.
The average length of a boy is 19.1 – 20.1 inches while girls on average tend to measure in at 18.9 – 19.8 inches at birth.
#2 – Labor May Be Shorter With Girls
According to a 2003 study  of over 8,000 births in Ireland, on average, labor for boy births lasted a little over six hours, while girl births took a little under six.
Women delivering boys were also more likely to require C-sections and have more complications during delivery.
One reason for this may be that boys, at birth, weigh more than on average than girls.
#1 – You May Eat Less When Pregnant With A Baby Girl
According to BBC News, a small 2003 study found that women carrying boys consumed more calories during pregnancy.
Lead researcher Professor Dimitrios Trichopoulos stated, “For evolutionary reasons – such as having to compete among themselves to gain the favors of women – males have to be bigger than females, and this phenomenon has its origins in the womb.”
 PubMed: Hyperemesis gravidarum and fetal gender: a retrospective study.; J Obstet Gynaecol. 2012 Jul;32(5):475-8. doi: 10.3109/01443615.2012.666580.
 CNN: Science backs up these pregnancy superstitions, By Cari Romm, Science of Us