One of the more intriguing observations about pregnancy is that births are sometimes reported to increase right about nine months after major weather events, such as hurricanes or snowstorms. While some have speculated that the sudden changes in barometric pressure that precede a storm could boost conception rates, no research has proved any such link.
Air pressure changes during air travel, however, have concerned doctors enough to issue warnings against women flying in late stages of pregnancy. According to the American College of Obstetricians and Gynecologists (ACOG), changes in cabin pressure, in addition to low cabin humidity on aircraft, can have various effects on pregnant women, including causing increases in heart rate and blood pressure.
In addition, such conditions on planes can cause significant decreases in breathing capabilities in pregnant women with weakened cardiovascular systems. While domestic air travel is nevertheless considered safe for healthy pregnant women through the 36th week of gestation, (35 weeks on international flights), women who are further along in their pregnancies should consult a doctor before flying, says ACOG. Women with medical or obstetric complications, or those at risk for premature labor or placental abnormalities, are advised not to travel by air.
Despite the concerns about air travel, barometric pressure changes on land are usually more subtle than those experienced when flying. Experts say spikes in birth rates that may sometimes appear after major weather events are more likely the result of stress or other factors than they are the result of air pressure changes.