Even with warnings from medical practitioners that her due date might not be spot on, it's very difficult for an expectant mom not to watch the date approaching with excitement and trepidation. The last few weeks of pregnancy can be physically uncomfortable and tiring, and many parents are more than ready to meet their newest family member. When the due date comes–and then passes on by–many pregnant mamas feel frustrated and begin to worry. It's not easy to wait for something this momentous, and nearly impossible not to worry about what could go wrong.
The more studies and research that experts do when it comes to pregnant women around the world, the more factors and variables they find as to how long a pregnancy will last. The length of a pregnancy can be influenced by an ever-growing mashup of both genetic and environmental factors. The growing anxiety of waiting for a fashionably late baby is also compounded by well-meaning family and friends who regularly ask why baby hasn't arrived yet. Some women may never know for sure why their baby wasn't punctual, but here are 15 things an overdue baby means (and 5 signs everything is normal).
20 The (In)Accuracy Of Due Dates
Sometimes the due date can be off by days or even weeks, and it all has to do with the way the due date is calculated. Doctors usually use Naegele's Rule, which estimates the due date in part based on the average length of a menstrual cycle–28 days, according to New York Magazine. Women's cycles can vary as much as a week, give or take. Naegele's Rule is also based on knowing the first day of the pregnant mama's last period, and many women don't keep track. Other factors like irregular ovulation can skew the due date. Only about five percent of women actually give birth on their due date.
19 Baby's Already Big
One potential cause of a fairly accurate due date is a larger-than-average baby. Fetal macrosomia is the term given for any baby measuring over nine pounds and 15 ounces, as per Mayo Clinic. Fetal macrosomia is difficult to predict, however, because so many factors potentially contribute to a baby's total growth. Doctors will often assume that if a mother goes past her due date by more than a week that she becomes at risk for birth complications related to a larger baby, and may make plans for a C-section, but fetal macrosomia is often diagnosed only to reveal that baby wasn't as large as the scans predicted.
18 First Time Or Second Time
It's so easy to compare pregnancies, but when doctors proclaim it will last 40 weeks, moms might want to keep in mind that's a grand average of all pregnancies–and it does matter whether it's the first or subsequent pregnancy, according to FitPregnancy. A first-time mama is pregnant 41 weeks and one day on average, yet a significant portion of first-time moms also end up going into labor early. It's common for first-time moms to be pregnant longer simply because the baby hasn't sent the “I'm ready” signal yet to start the labor process. With each pregnancy, the amount of time a woman is pregnant tends to grow shorter.
17 Potential Placenta Problems
One potentially scary prospect that doctors will warn expectant mothers about is a placental failure or placental insufficiency, but it may not be tied to timing as much as doctors proclaim, as per Birth Savvy. The evidence that placental insufficiency is due to an overdue birth is inconclusive. Other factors like the mental and physical health of mom and her diet and nutrition may actually contribute more to a healthy or unhealthy placenta. Nevertheless, doctors have made a clear link and will utilize the fear of placental failure to push for an induction. The mother should consider her overall health when deciding whether induction is right.
16 Mom's Height Matters
Most women would be shocked to find out that one of the factors that contribute to the length of time they'll be pregnant is their height. Shorter women tend to be pregnant for a shorter term and are more likely to go into pre-term labor than taller women, according to Health. It's only one of many factors, but recent studies indicate that taller women tend to have larger babies and carry them longer. If a tall woman is also a first-time mother and the due date doesn't take into account her irregular cycle, she could go several days or even weeks past her due date and still have had a normal pregnancy.
15 Not Enough Amniotic Fluid
Amniotic fluid levels steadily increase throughout the pregnancy until around 34 to 36 weeks, at which point it generally declines until birth, but many doctors will cite the dangerously low levels of amniotic fluid at 40 weeks and beyond when recommending an induction, according to Science and Sensibility. There are multiple factors that can cause an accelerated decrease in amniotic fluid, including maternal dehydration or placental insufficiency. The difficulty lies in the doctor's ability to assess just how much fluid is actually present. The most accurate test is also extremely invasive, involving injecting dye. Other ultrasound measurements have a high degree of inaccuracy–they may only identify low fluid 10% of the time.
14 Some Ovens Bake Faster Than Others
If pregnant women tune out the doctors' 40-week mantra and really stop to consider all the factors that contribute to the length of their pregnancy, they might be more comfortable going into week 41 or 42. Shorter women tend to go sooner than taller women, but smarter babies stay in longer on average, and health conditions like diabetes, high blood pressure and when mom actually ovulated in the first place can all influence when go time rolls around, as per WebMD. Other things like genes and environmental stress also affect how long baby stays in, and there may be other factors that haven't yet been identified that can delay the delivery.
13 Meconium Mess
Meconium aspiration syndrome (MAS) is more likely to occur after mom has passed the 40-week mark, as per Healthline. Meconium is a dark greenish-black stool that forms in baby's intestines before birth. Usually baby passes this stool in the first day or two after delivery, but occasionally he may pass meconium while still in utero. It then mixes with the amniotic fluid and he can aspirate it. MAS can cause difficulty in breathing once the baby is born, and could even cause a blockage. The meconium will usually be suctioned out by the doctor and the baby may be observed to ensure that there was no overexpansion of the lungs.
12 Circle Back To Cycles
Naegele's Rule is based on the average woman's menstrual cycle and assumes a regular 28-day interval. Many women's menstrual cycles don't fit the average, but doctors don't always make adjustments to Naegele's Rule when calculating their due date, according to CYS Online. Naegele's Rule is calculated based on the first day of the expectant mother's last menstrual period. To this one year is added, then three months are subtracted, then seven days are added back. Many women experience spotting after they've already conceived, or might not remember exactly when their period began. They may cycle irregularly or have ovulated a day sooner or later than the average.
11 Talking About Induction
One issue of concern that mothers may have once they pass their official due date is that some doctors will immediately begin discussing induction. Induction usually involves at least one of several procedures and often includes administering artificial oxytocin-like Pitocin, as per Evidence Based Birth. At issue for many mothers is whether induction is more likely to lead to possibly unwanted medical interventions–like a C section–but doctors often feel strongly that because the risk of stillbirth begins to go up once mom has passed 40 weeks, the induction is worth the risk. The rate of increase for stillbirths varies depending on the study.
10 Fundal Height Failure
Even if the expectant mother knew exactly when the first day of her last menstrual period was, the due date could still be off. Measuring the fundal height is often used to make adjustments despite the high degree of variability. The doctor measures from the top of the pubic bone to the top of the uterus to get the fundal height, but what many moms don't know is that it isn't a good guide for the actual gestational age, according to What to Expect. It's normal for moms to measure up to three weeks smaller or larger than expected, but the doctor still may adjust the due date.
9 The Age Factor
The older expectant mother is a much more common patient in doctors' offices these days. Women over the age of 35 are considered older mothers and doctors generally treat these pregnancies as tending to have more risk. It's difficult to know whether older women really have shorter or longer pregnancies relative to younger mothers, because in the US especially, medical professionals often begin intervening as early as 37 weeks and usually no later than 39 or 40 weeks, as per Evidence Based Birth. One study did find that on average a day could be added to the length of gestation for each year of age, according to Science Daily.
8 Gender And Gestation
When everything is looking good at the checkup, the expectant mom feels good about the accuracy of her due date but that day comes and goes with no signs of labor, it could be based on the gender of the baby. Boy babies may take a little longer in the womb, according to the Mayo Clinic. A different study recently indicated that baby boys are also more likely to be born pre-term, as per Nursing Times. This could imply that baby girl births cluster closer to the due date, while baby boys are a bit less predictable. Boys that do stay in past the due date tend to be larger.
7 So Many Checkups
During the majority of the pregnancy, most women see their doctor once or twice a month. From week 36 to week 40, most low-risk pregnant women see their doctor once a week, but once the due date has come and gone, there may be more checkups. Some doctors will have the expectant mama come in every couple of days, or may check internally to see if the cervix is showing any signs of readiness. Another test that doctors routinely do when baby's overdue is fetal heart monitoring, and they may also try to determine how much amniotic fluid is present, as per Mayo Clinic. The assessment of amniotic fluid with a fetal ultrasound isn't always reliable, however.
6 Running Late Is A Family Trait
If a woman's mother went past her due date when she was pregnant, chances are her daughter will, too–maybe. Overdue babies do seem to run in the family, but researchers explain that expecting mothers should take that with a grain of salt, according to What to Expect. While mom might have counted it as 42 weeks, it's also less likely she had a correctly calculated due date or correlating ultrasounds that can help fine tune the due date. It's not a guarantee in every case, but a family history of arriving late to the birth party combined with other factors could mean waving at the due date as it passes.
5 Vital Signs Are Normal
By the 40 week mark, most pregnant women are seeing their medical provider at least once a week. They check for any emerging issues, like high blood pressure and even listen to mom's heart and look for signs of high blood sugar to rule out preeclampsia, peripartum cardiomyopathy or gestational diabetes, as per Self. If mom's vital signs are normal, she's not experiencing any severe pain, fever, or other unusual symptoms, then doctors are often content to let the days pass and wait for labor to begin on its own, provided baby doesn't appear to be showing any signs of distress.
4 The Absence Of Protein
The doctor may periodically have the expectant mother give urine samples. Early on in the pregnancy, the doctor might be checking to ensure there's no protein in the urine, as this might indicate a urinary tract infection or problem with the kidneys. Towards the end of pregnancy, however, protein in the urine often points to preeclampsia, according to BabyCenter. Protein in the urine along with a high blood pressure reading is a good indication that preeclampsia may be developing. If the urine sample is clear of protein and mom's blood pressure isn't unusual, then it's safer to allow her to wait for baby to come on his own.
3 Feelin' Good In The Neighbourhood
By the time they’re in the last few weeks of their pregnancies, most women don't feel particularly comfortable, but if they feel pretty good considering they're still pregnant, then that's a good sign and doctors will be more likely to let things continue to run their course, as per What to Expect. Up to 70% of overdue pregnancies aren't actually overdue, so if mom is feeling good, she might actually be feeling some of the nesting tendencies that many moms report. Nausea, fever or new or serious aches and pains should be reported–these could be signs of an infection, and that's bad news for baby so close to delivery.
2 Room To Grow
A number of women who breeze past their due date are given an ultrasound just to check on baby and allow the doctor to guess at an estimate of the amount of amniotic fluid. They'll often take measurements of the baby as well. If there's room and baby is kicking and moving, then the doctor might explore whether the due date was off. A few extra days in the womb can be very beneficial for baby, as it gives her lungs, liver and other organs more time to mature, according to Belly Belly. Even going a week or two overdue doesn't automatically result in a huge baby.
1 The Situation Is Fluid
As the due date approaches, many doctors begin to worry about the amniotic fluid and may order an ultrasound so they can gauge how much fluid is present based on measuring any pockets they see, as per Science and Sensibility. These tests are imperfect, however, because they are estimations, and the index they're based on is actually fairly arbitrary. If mom doesn't show any signs of rupture of the membranes, then she'll likely be reminded to stay hydrated and wait. Ruptured membranes don't always gush amniotic fluid–many women describe it as feeling like they've wet themselves. Once the membranes have ruptured then the countdown begins–infection can set in.
References: New York Magazine, Mayo Clinic, FitPregnancy, Birth Savvy, Health, Science And Sensibility, WebMD, Healthline, CYS Online, Evidence Based Birth, What To Expect, Evidence Based Birth, Science Daily, Mayo Clinic, Nursing Times, What To Expect, Self, BabyCenter, Belly Belly, Science And Sensibility